The development of my favourite the Gold Star.
When I came to work at BSA in 1952 there was no programme of development for the Gold Star, at that time we seemed to just pick up problems as they developed and try to fix them. The 350 Gold Star did quite well in the Clubmans TT, their power output averaged 27 to 28bhp. There were a number of problems causing retirements in the races the most serious of these was the heads burning near the joint face. Cyril Halliburn who was my assistant in those days suggested it was the porous castings and wanted to blame the foundry, strangely, the foundry did not deny this but said they did not understand what was wrong. In the Isle of Man during the practice period several of the heads were discovered to be 'burnt' when removed for examination. My opinion was that the joint at the Back to top of the cylinder barrel and head left an annular gap varying from .005" to .035", the wider joints trapped some gas which detonated causing the burnt heads. The normal gasket was a fairly thick copper asbestos affair, the production people claimed an inability to hold tolerances on cylinder barrel spigot and cylinder head spigot joint to less than .015", the gaskets also varied in thickness. It must be remembered that this gasket also had to make an oil tight joint at push rod tunnel. My solution was to use a ‘Plexseal’ joint, this gasket was formed of aluminium foil .002" thick stuck together to form a laminated gasket whose thickness could be varied by peeling off a layer one at a time to get a perfect joint, keeping the annular joint gap to between zero and .002" and yet still sealing the push rod tunnel. My suggestion was accepted but it did not reach production until later in 1952 or early 1953.
Another quite serious problem was the crankcase breather, situated in the timing case. A small pen steel disc acted as an automatic flap valve, unfortunately it did not work efficiently if at all at high speeds, thus allowing a lot of engine oil to blow out of the crankcase. Some of the riders ran out of oil due to this, all complained of the oil all over the rear tyre. My solution was to build a rotating sleeve in the timing cover driven by a peg on the magneto pinion, this was made in time for our testing at Montlhery in 1953. This mechanical breather was very successful as it kept the pressure in the crankcase about 4" - 7" below atmosphere at all speeds, which kept the oil in the engine and rear tire cleaner. Surprisingly this breather contributed a slight increase in power of 4bhp over the flap valve. The best timing was for the port to open 20 degrees before BDC on each stroke. Another problem was the occasional exhaust valve breakage which usually did quite a bit of damage.
The Research dept came up with the answer here. A special nickel alloy Nimonic 80, after its use I never saw another one break. A difficult problem was valve springs. I would have liked to have gone to hairpin springs but this was not possible. We tried all the usual approaches, talking to Terry's, the spring experts, even our friends at Rover designed a spring to try, our own spring shop tried various tricks and materials but we were getting very little progress, then Hap Alzina sent some S&W springs for the twins, I decided to try these in a Gold Star and they worked beautifully right from the start, giving us a big increase in maximum revs. I suspected shorter connecting rods might show some advantages in several ways, firstly by changing piston motion relative to crankshaft rotation, also shortening the whole engine including the push rods.. We built some 350 engines using A10 and A7 connecting rods, these showed an appreciable increase in performance but we could not be sure what was due to the shorter connecting roads or the fact that they were lighter and had plain bearing big ends. Mr Hopwood agreed to have some special forgings made up using the shorter dimensions, this enabled us to carry out some direct comparisons which showed that we had got a small increase in power through the lighter alloy rods and plain bearing, but that a worth while increase came from the shorter length rod.
These tests became useful later on when we wanted to find out whether a one-piece crankshaft offered any advantages over the built- up flywheel assembly. It showed excellent results especially at high revs, the only problem experienced with one-piece crankshaft was the connecting rod detachable bearing cap. It is very difficult to make a connecting rod with a detachable cap as strong as the one-piece rod. These 1952 Gold Stars had push rods made of solid dural with steel caps rivetted on. We substituted some 3/8 dia T4 tubing with lighter end caps pressed on. You can imagine how much lighter these were. I made, a sketch of a rocker spindle which had the rocker bearing portion machined eccentrically and the Drawing office made an official drawing and we were able to eliminate the heavy valve adjuster that kept the oil in the engine and rear tyre cleaner. Surprisingly this breather contributed a slight increase in power .4bhp over the flap valve. The best timing was for the port to open 20 degrees before BDC on each stroke. Another problem was the occasional exhaust valve breakage which usually did quite a bit of damage
The lower half of the Gold Star engine was basically similar to the 1938 M24 Gold Star and to the B33 post-war iron 500, although the crankpin assembly was changed quite a lot, the flywheels were always forged steel. The pre-war and the immediate post-war ZB Gold. Star differed quite a lot, including having bore and stroke changes. I liked the non-detachable rocker box of the ZB, even though it was a bit of a fiddle getting the head off with the engine in the frame. This earlier design avoided the oil leaks that later Gold Stars sometimes experienced at the rocker box joints. The later big fin Gold Star engine which I suppose is the version most beloved by enthusiasts, came about in the following way. After all the debacles we had been having with the twins some of which I have described, it was decided that as we were making a new cylinder head for the 350 Gold Star, we could afford a 500 version of it. Brian Jones of the Drawing office, a very capable and gifted young fellow, set about designing the new head. Mr Hopwood told him to consult with me on it so every day I would confer with him his office, look over his shoulder and make a few suggestions. He was decent enough to incorporate some of them.
One of my ideas was that of sloping the fins between the two rocker box joints to get an air flow across the dead space on Back to top of the head. Of course we did not know what the air would do but it worked well in practice. I am always a little skeptical about the air flow paths around a motor cycle cylinder head particularly when mounted in the frame. The new big fin heads both 350 and 500 had a cooling fin area of about 520 square inches. We measured it by getting an apprentice to cut out pieces of squared paper to match all the fins then laboriously compute their combined areas. We were.of the opinion that 520 square inches should be just adequate for the 500 version and possibly over generous for the 350. I do not think that at that time we visualised using one of these heads on a 250. Some interim heads for 1954 Daytona models were made by using 350 castings machined to suit 500, these gave more power than the normal 500 heads due to better down draft inlet ports and slightly more fin area. Of course they were a bit thin in places and tended to crack. The new heads were ready for the 1954 TT and were an instant success, and by using larger inlet valves the 350 power was increased from about 30 to 33-34bhp'.
The timed breather was also used and the eccentric rocker spindle and Nimonic 80 exhaust valves. The improved valve springs and the laminated head gaskets all contributed to a most reliable engine. The 500cc version gave over 44bhp in IOM trim. These engines all had the shorter connecting rods, the 500 had oval flywheels to get piston skirt clearance and still have some flywheel effect this later however proved to be unnecessary. During all this activity on Gold Stars many other developments were going on. We tended to let the mechanics specialize as they seemed to be more efficient in this way. Reg Wilkes for example did most Gold Star development, Arthur Butler worked on A7 and A10 development. Arthur Bridgewood worked on the 500cc overhead cam twins and the MC4. Bill Bently exclusive on MC1. Bert Hole worked on the twins . Alan Sandilands did some work on the MC1 and a lot of special projects like a scrambler C12, special short stroke engines with one piece crankshafts. Jimmy Gibbard spent his time as a machinist making special parts for the shop. Jake Turner came in later as both machinist and mechanic and did a lot of work on 250 Gold Stars, was also responsible for machining the straight port head for 350 Gold Star. All of them at some time or another worked on the 'experiments to find optimum bore and stroke dimensions. We did some experimenting with chrome plated cylinders which was promising but inconclusive.
Due to the temporary shortage of aluminium because of; the Korean War some Gold Star cylinders were, cast iron, we were instructed to evaluate these in case the factory was forced to use them. They were terribly heavy, about three times the weight of the standard alloy cylinder. Much to everyone’s amazement we got slightly more power and no overheating, the piston rings also appeared to run better in the iron cylinder, which set me thinking. When the original tests were completed we knocked all the fins off the iron cylinder and turned it down to a heavy sleeve in the lathe,, then bored a standard Gold Star cylinder jacket to be just a bit smaller than the outside of the iron sleeve. The alloy jacket was, heated up and dropped on, making a nice tight fit, a flange had been left at the bottom of the line to sit on crankcase face. As the line's had been left about *" thick, the Back to top of it made a good seat for the cylinder head. Due to all the machining and shrinking process the bore had distorted slightly and the rings did not bed in very well, so we had it lightly ground true which left it about .002" oversize.
On test it performed very well, more power, better oil control and no scuff marks as we got with the standard austenitic liners. I discussed this with 'Brico' the piston ring people and they said they were not surprised and agreed to make us two special thick sleeves for further testing, one using the austenitic material and one plain cast iron. We gave these extensive testing, the rings bedded better and controlled oil consumption better with an iron sleeve. The tests were repeated with 350 Gold Star, again the plain cast iron showed up to advantage.
The Design office were interested but reluctant to admit that austenitic was not necessary. They changed to the thicker liner in production, but I am not sure whether they changed the material. Early in 1953 we tested some chrome plated Back to top compression rings from Brico in a special 350 Gold Star we had built for Charlie Salt. This engine had what was then the new eccentric rockers, a plain big end bearing in an alloy con rod. This engine was in the 350 Gold Star we had taken to Montlhery for high speed testing. It performed very well but the chrome ring even after hours of running never really bedded in. We reported this to Brico and they said not to worry as they were grinding these rings with a slight taper degree on the face, and that we should find them ok. After trying these new taper face rings we found them very much better and ultimately got almost 34bhp from this engine. Unfortunately the connecting rod cap broke up in the Junior TT due to the self locking nuts coming loose.
Following a hot tip I had received, we built a 350 Gold Star with cylinder axis offset 3/8" to the rear, this gives a peculiar motion to the piston, with the effect of a short connecting rod 4 3/4" long and 8" long going down and 1.4 increase in bhp, but it was a rough engine. Due to the good results I had had using a dural (RR56) connecting rod with plain connecting rod bearing in my Rudges I wanted to try this in a Gold Star. We had made a connecting rod of this type, made to my drawings, it turned out to be reliable and smooth but very little more power than the standard steel rod. We used this engine for comparison tests of various parts and ideas for several years. It was finally sold for scrap when I left BSA Quite a bit of testing was of moulded bakelite big end bearing cages, as they would have been a lot cheaper to produce than the dural cages used in production, but they failed at high RPM.
The original Gold Star BSA got its name by lapping Brooklands race track at over 100mph in 1938 ridden by Wal Handley, a very fine rider. This was followed in 1939 by an alloy engine version called a Gold Star, it had 82 x 94 bore and stroke. In 1954 we made a modern version of this engine to see if the longer stroke showed any advantages, using M20 flywheels, a pre war piston and modern cylinder sleeved down to 82 mm. It was a disappointment as it did not pull any better and gave 42bhp. Charlie Salt & I rode it around Oulton Park. It was also tested as a scrambler by Dennis Hardwick and someone in the Competition department. After a final strip down and rebuild we got 4bhp which wasn’t bad but at the time the standard 500 Gold Star was giving 45-46 quite readily and as much as 50bhp as flash readings. We made a range of 350 engines with bore and stroke ratios varying from 63 x 112 to 71 x 88 and 76 x 76, 8.x 66 and 85 x 61.5.
Not all at once but fitted in with other testing, the 82 x 66 engine was built in two forms both used one piece crankshaft plain big end bearings and outside flywheels. The first engine had a higher compression ratio and orthodox intake port merely straightened and given a little more downdraft. The best reading on this engine was 38~bhp, but one day it seized up so suddenly that the flywheel inertia twisted the crankshaft making it impossible to strip. The next version had bigger diameter mainshaft and lower compression ratio, due to unavailability of the pre-war Gold Star piston we had been using, this engine was very reliable and we did all sorts of tests using various carburettors, silencers and cams.
The best power with racing set up was 36bhp at 7250 RPM and 36.1 at 7750 RPM. The most interesting was the power obtained with road cams and silencer and monobloc carburettor 27.3 at 7000 and still pulled strongly at 2500 RPM. From these test in 1953-54-55 I became convinced that short strokes were the way to go. Modern 1988 motor cycles would seem to bear this out. The Gold Star head gasket joint system is rather unique and merits some comment, the push rod tunnel construction called for something other than the classic four stud joint to prevent oil leaks. The system adopted consisted of four long studs coming up from the crankcase in orthodox fashion, plus four more short bolts that simply united barrel and head from below, one bolt in the push rod tunnel the others at front and rear and on the left side. All eight bolts screwed into bronze inserts which are themselves screwed into the head casting. The system was not completely successful as we sometimes got leaky joints. Another snag was the difficulty in tightening the rear bolt, sometimes it was necessary to remove the magneto in order to get at this bolt, so we often left them out with no ill effects. At one time we went to only five fixtures, with no problems. on our special engines we adopted the final variation on these themes by making four hollow steel tubes to replace the crankcase studs and ran four bolts down from the head into the internal threads in the four tubes, which had external threads at their lower ends where this four bolt arrangement was fully proof against gasket blowing and greatly simplified head removal, especially with the engine in the frame. This last system would have been cheaper, but in spite of this was not adopted.
Connecting rod breakage used to be a frequent Back to topic of conversation amongst racing men as breaking at high speed can lead to some terrifying moments, besides doing a lot of damage. I believe the forged steel rods in BSA engines were outstandingly good. A number of Manx Norton riders I know used them because they found them more reliable than some of their original equipment. BSA had a great deal of know-how when it came to forging. No one else in the motor cycle industry forged their own connecting rods, other makes had to go to outside supplies like Laystall or Garrington. Naturally when you make parts yourself you have more control and you can try different components. We were lucky in that we had a good smithy and good people working in it.
About the time Lucas came out with a new racing magneto of the rotating magnet type, it was supposed to be less affected by vibration and more reliable but I was not very, impressed with its performance, it also had less range of advance, and retard. Personally I preferred the BTH magneto. We borrowed a 350 Manx Norton engine in 1956 which had a good power curve, we got 38bhp and very good torque with it, rather better than our own engines. On examining the cams we found that due to being a double overhead camshaft design there was very low reciprocating weight, enabling very quick lifts to be used without very 'long' timing. This particular Norton was a square engine 76 x 76 with squish piston. We built a Gold Star engine to these dimensions to test the so called squish effect using a Norton piston in a modified BSA head, this gave us 36.4bhp but we could get practically the same power with ordinary non-squish combustion chamber, maybe it only works with higher compression ratios, ours was 9.0: 1
The quality of mechanics who were employed in development was very high, there was not much they could not do. Alan Sandilands once made some prototype cams by hand. Jake Turner was a terrific machinist, very fast and accurate, he also thought up the method of making a virtually straight inlet port. Reg Wilkes was the artist who would fettle a piston and head until he got the maximum power that was possible.
We made some alloy tappets that were very light and worked very well, they seemed to be very compatible with the hard steel cams, the only problem was after about 500 racing miles they broke, but while they worked they were good. I feel sure that if we had been able to make larger diameter guides and stems to suit they would have been very satisfactory. Charlie Salt once set out to design a new crankcase for the Gold Star using a high camshaft, but it had to look like a BSA he was told. Sunbeam and Rudge had both made high camshaft engines pre-war with chain driven camshafts.
At various times we had problems with A10 and A7 connecting rods especially when used in the plain bearing Gold Star. We were trying to get away from split pins and castellated nuts and trying various patent self-locking nuts. The only one that was successful was the pinnacle nut which had a steel diaphragm to lock the nut. One of my ambitions was to utilise all the successful ideas we had used on the Gold Star and make them standard parts so that the B31 and B33 would use .the same connecting rods and valve sizes, push rods made of tubular alloy instead of solid, eccentric rocker spindles and the simple Gold Star rocker, but still retaining the iron heads and cylinder barrels. Unfortunately the production people could not see the benefit of these ideas. We did extensive testing with floating bush big end bearings mostly in the 500 Gold Star on the basis that if it stood full power and revs in that, it would certainly last in a lower power engine. The floating bushes were very much cheaper to make. During road testing at MIRA. Barry Stormont did 116 miles in the hour which was something of a record for us. It was in winter time and he was literally frozen stiff, we had to take him out to a warm cafe to thaw him out.
All through a long test programme, using factory bushes made by Glacier bearings we had no trouble, but when we started using their production samples they were almost useless, so we had to F->rop the whole scheme, which was a pity. We also tried a large diameter wrapped bush running on a large crankpin, we tried both bi-metal and copper lead, they were both satisfactory, but the larger crankpin was so rigid we had trouble aligning the flywheels. All these plain bearings really need a large paper filter built in to the engine, but all we had was a small tecalemit filter on the return oil line. Although either of these bearings would have shown a big economy I did not receive much encouragement. I think the factory was scared to make a change, although they already had these plain bearings in the twins during testing of the floating bush connecting rod bearing we had problems with over oiling. It appeared that too much' oil was being thrown up to the cylinder and piston, this we corrected by reducing the diameter of the flywheels and chamfering them.
The following summary of the development of the Gold Stars may be of interest.
1952 350cc
27 - 28bhp
1956 350cc
35 - 36bhp
1952 500cc
35 - 37bhp
1956 500cc
44 - 46bhp
We felt that these increases came from higher revs which in turn came from lighter valve gear, better springs, larger carburettors, higher compression with cooler running due to the big fin heads plus higher octane fuel. About 1955 the desire developed for a better brake for our scramblers. Since the management wanted to avoid spending money, as usual it was decided one brake would have to do for both Clubmans TT and racing Gold Stars-and Scramblers. Dennis Hardwick wanted a small intake for the scramblers, Charlie Salt and I wanted a big brake for the Clubman. We compromised on a 19O mm brake on Charlie’s suggestion, who told me he was banking on a belief that Hardwick would not know how big 190mm really was. As it turned out Hardwick didn’t. So we came out with this fairly large brake, with wide shoes which was used for some years afterwards although in my opinion it was not as good as the earlier cast iron drum with ribs around it. That was the best Gold Star brake. Charlie did not like it himself and he blamed Hardwick for the fact that it was too small as he would have preferred 200mm diameter. The l90 mm brake was designed by Charlie and it turned out to be rather heavy for its size.
Sunday 25 January 2009
Roland Pike Autobiography - Chapter 22
The Terrible Twins
I have never liked the air cooled vertical twin, but they looked neat, were simple, had an even firing, smooth exhaust note, fitting neatly into the same frame as their predecessors, the singles. The vibration was terrible, it seemed worse than the single, at least it was more noticeable. To my mind the head joint on all vertical twins with one-piece heads and cylinder block was marginal and subject to distortion. At BSA we must have done a fantastic amount of work on twins, judging by my notes. BSA had made up their minds that the twin was the motor cycle engine of the future. Every time I rode one it gave me the willies - the vibration was so noticeable. We tried all sorts of cures to get rid of the shakes and I still think our best ever effort in that direction was a short stroke 500 we made in 1953. Charlie Salt & I ran and ran it until we wore it out but no one seemed interested in it. This short stroke engine was a 500 A7 using a 650 head, barrel and pistons slightly modified. The crank was machined from the solid. This arrangement gave a 70 x 64.5 bore and stroke and instead of having a bolt on flywheel it had a triangular bob weight machined in the centre of the crank and discs next to the journal bearings. It was a very smooth running engine, both on the dyno and on the road. Power output was similar to the Star Twin, using 7.25:1 compression ratio.
With further tuning and lighter valve gear it gave 36bhp at 7000 a specially developed two into one exhaust system, we got as much as 39 horsepower at 7000. It was a most exciting machine to ride, as you accelerated it went on a normal power curve, then suddenly the exhaust note would change and it would 'yowl' right on up to maximum about 107mph Back in 1953 on low octane petrol this was quite an exciting performance on the road. Charlie and I enjoyed that engine.
The so-called Star Twin camshaft was a sporty one designed I think by Jack Amott although the design office never gave him credit for it. It was quite useable on the road with silencers fitted and also useful with open pipes. The fellows in my shop told me Jack did all the work on cams and I have no reason to doubt their words. Later on we went to the Daytona camshaft which was really a race cam and not very good at low revs but good at high speeds. Amott did design a racing cam for the twin, but we were unable to make it work properly, it was too radical and hard on valve springs. Reg Wilkes mentioned that if the drawing office had stuck to Jack’s original design they would have been all right. I asked to see Amott's original design and Reg got his camshaft out of a cabinet and showed it to me. It had a much larger base circle than the drawing office version, although to be quite honest I could not see what effect this would have. Wilkes suggested I try it sometime, he was sure it would work better and it did. It was still pretty radical. I never could understand why the drawing office decided to change the base circle diameter. One of the disadvantages of a larger base circle is a higher rubbing speed on the other hand you can get a smoother easier ???
Twin camshaft problems. Whilst working at BSA Dennis Lashmar carried on racing my old 'Pike BSA' with the alloy twin engine. I think he had one good win on a wet day at Snetterton, when it ran cool enough not to blow up. Latterly whenever we went to Silverstone or anywhere to watch him, he finished up sliding along on his backside at about 100mph with a broken crankshaft. This was too dangerous I considered. Once just after the massed start at Silverstone, with the pack all bunched up and approaching Woodcote corner at over 100mph the Beesa suddenly seized and he was sliding along with bikes all round him! I told Mr Hopwood that if we could not do something about the crankshaft breakages we should drop the racing twin. He pointed out that as far as Lashmar was concerned it was his own bike and he could do what he liked with it, but the policy of the factory was to make a twin. I felt we should make a new crank for it to which he agreed and wanted to know if I had any suggestions. By this time Group Research were in the picture at BSA and they demonstrated to me in ten minutes what I had suspected for years. They came up with some very good ideas. One was that the crank needed larger crankpin journals .which would make it stiffer and get away from the frequency at which it now vibrated. Mr Hopwood agreed that their suggestions were fine for 1955 but at that time we had to use what we had. He was interested to know if any other suggestions and Group Research said to put a rolled radius around the ends of each crankpin. They demonstrated by putting a standard crankshaft on vee blocks over the Back to top of the electro-magnetic vibrator they had built.
Then started some sort of motor generator. The noise was like standing next to a jet engine at the airport, it went into a scream and from a scream to an outer pitch sound, onto another phase even higher, then they brought in the electro-magnetic vibrator and the whole place began to buzz. The frequency of the vibrator was adjusted to a multiple of 6,600, the crank vibrated with a high speed buzz, inside ten minutes there was a loud bang, the crank fell in two parts, broken at the usual point, showing the same sort of fracture that we had experienced after three hours running at 6600 RPM. It was a much quicker way of testing a crankshaft and without wrecking an engine. Next they set up one of their special cranks, with the rolled filet radius on the crankpin, it was subjected to the same test, buzzing away on the vee blocks, ten minutes passed, thirty minutes and it was still in one piece. I got tired of waiting and asked to be informed when it broke. It did not break and after one hour it was still good. I was very impressed and so was Mr Hopwood but the factory again did not seem interested, perhaps they could not believe it. This rolling process consisted of applying a ball ended tool to the radius under high pressure in a big lathe.
A few cranks were made, some for research, some for use on the dyno. It seemed fantastic that this simple process could make such a difference. Many years later when I was working for Volkwagen in the USA. I discovered that they cured a rash of broken crankshafts on the 1965 truck engine by the same procedure, except that they did not use a ball, but a small roller to form the radius. It cured the problem for Volkswagen.
Twin engines for Formula 3 We made a number of A7 race engines for this small race class in 1953. They were set up to run on alcohol fuel but were not very reliable and although we got close on 50bhp were repeatedly beaten by Norton singles doing far less. We actually 'borrowed' a 500 Norton engine designed for a formula 3 car, it pulled 42bhp but had 39 ft lbs of torgue against our 36 ft lbs. Part of the trouble with our engines was the installation, they did not get enough cooling air and in one case they had a restricted oil supply, using a long small bore hose from the tank to the engine, the sticky Castor oil simply would not flow fast enough. Another problem was at the head to cylinder block joint, there was a tendency when very hot for a slight blow across to the oil drain holes thus pressurising the crankcase, this blew oil out of the crankcase at every possible point. The cure was to fit small hollow dowels into the head and barrel joint, thus rigidly locating the head, and keeping gas pressure out of the crankcase.
The single overhead camshaft A7 In 1952 they were working on a single overhead camshaft 500 twin. It was a handsome engine with alloy head and barrel, fine pitch finning, exhaust pipe held to the head by nuts. The single overhead cam was driven by bevel gears and a shaft running up what would normally be the push rod tunnel, the valves were operated by rockers. Arthur Bridgewood was working on it in great secrecy in a little shop at the end of the test shop, he had to put up with the noise and fumes of engines being tested. At this point in time it gave the same power as the A7 push rod engine and broke crankshafts with equal regularity. The camshaft was lubricated by the rocker feed which was completely inadequate and of course it wore out cams and nd rockers. Doug Hele suggested using a single wide cam as they did on some Ariels. This cured the rapid wear but the performance suffered due to the geometry of the rockers to cams, one rocker being a trailing rocker, the other a leading one this giving different opening diagram for each valve. I personally felt that the engine could have been made to go if I had been given more freedom as I had with the Gold Star and MC4. One problem was excessive oil consumption due to an accumulation of oil in the rocker box which ran down the valve guides. This we cured by using a C11 oil scavenger pump to pump surplus oil direct to the tank. The feed side of the little oil pump was used to squirt oil through 1/16th holes on to the cam lobes, this cured the rocker and cam wear. At this point we needed a stronger crankshaft and a different design of cams to take advantage off the overhead cam arrangement. By this time Mr Hopwood had lost interest in the engine and said he did not think it would ever be any good, so scrap it. I think that’s what finally happened to it.
The A10 was if anything worse than the A7 when it came to vibration and crankshaft breakages because of its longer stroke. Actually most complaints were about the A10. Although the A7 was the one we raced so that we were more intimately involved in its development. BSA brought about their own demise by their attitude to progress. A favourite saying of Mr Leakes was "Don’t let us be pioneers". Back in the dim and distant past they had lost money on a few experimental ideas that had not worked and that had never been forgotten. Nevertheless when you are the biggest motor cycle manufacturer s in the world you have got to do some pioneering if you want to stay on Back to top. You cannot leave it to small firms like Velocette, who introduced foot gear-change, a successful spring frame, eccentric rocker spindles, a production overhead camshaft engine and many other innovations.
Alloy heads for the twins About the beginning of 1954 it was decided to make a production version of the twin with an alloy head, we had made experimental ones before for the racing people. The head had shrunk in valve seats which gave very little trouble but the spark plugs fitted into bronze inserts screwed and pinned into the head, these persisted in coming out when the plug was removed. I persuaded Mr Hopwood to use long reach plugs screwed directly into the aluminium head, this was very satisfactory. At one stage we could not make a decision on which was best, a single inlet port and one carburettor or twin ports and two carburettors, on the dyno there was very little in it. The first of the Star twins had twin port heads with detachable manifold, it could be used with either one or two carburettors. In point of fact the difference in power is only worth while when running on open pipes. Twin carbs and their cables have to be carefully adjusted to keep both cylinders pulling equally at small throttle openings and just off idling, which is a nuisance to the rider at best, assuming he can cope with the bit of DIY mechanical skill necessary.
After a year we had improved the port configuration and it ran so much better with one big carb that the twin carb option was dropped. We had found it useful to measure the capacity of the inlet ports and check on performance, about 142 to 150cc's gave optimum results. If an engine was down for power we often found the ports undersize. Like all aluminium cylinder heads, these expanded a lot with heads and at the outset we experienced stretched or broken head bolts. These bolts went downwards through the head into the iron cylinder block and would usually break at the root of the last thread, which was the weakest point because it took all the stretching. To overcome this we quite simply put the bolts in a lathe and reducing the diameter of the pIain portion to 10% less than the diameter of the root of the thread. This meant that the thread was no longer the weakest point and that the plain portion could stretch without exceeding its elastic limit.
This was completely successful on the first attempt and no more trouble was experienced with the bolts. They could stretch when the head expanded and return to their original length as the head cooled own. When the new twins were going into production however, Alan Jones who was Works Manager at that time phoned me to say they were unable to make the head bolt as needed, despite my pointing out that we bad found them necessary, he just continued to say they were unable to make them. I went on with my work and forgot about the matter, but I did not have to wait long, within a few hours the motor cycle test shop foreman was on the phone to me complaining the head bolts of the new twins were breaking right and left, so I referred him to Alan Jones. Mr Jones reiterated they were unable to make the bolts we had designed. Prior to this last call I had taken the precaution of calling the drawing office to say that Jones would not follow their drawings of the bolt thus securing an ally. Alan Jones got no sympathy when he had to pull all the bikes concerned back, dismantle the engines and use the bolt we had specified.
I have never liked the air cooled vertical twin, but they looked neat, were simple, had an even firing, smooth exhaust note, fitting neatly into the same frame as their predecessors, the singles. The vibration was terrible, it seemed worse than the single, at least it was more noticeable. To my mind the head joint on all vertical twins with one-piece heads and cylinder block was marginal and subject to distortion. At BSA we must have done a fantastic amount of work on twins, judging by my notes. BSA had made up their minds that the twin was the motor cycle engine of the future. Every time I rode one it gave me the willies - the vibration was so noticeable. We tried all sorts of cures to get rid of the shakes and I still think our best ever effort in that direction was a short stroke 500 we made in 1953. Charlie Salt & I ran and ran it until we wore it out but no one seemed interested in it. This short stroke engine was a 500 A7 using a 650 head, barrel and pistons slightly modified. The crank was machined from the solid. This arrangement gave a 70 x 64.5 bore and stroke and instead of having a bolt on flywheel it had a triangular bob weight machined in the centre of the crank and discs next to the journal bearings. It was a very smooth running engine, both on the dyno and on the road. Power output was similar to the Star Twin, using 7.25:1 compression ratio.
With further tuning and lighter valve gear it gave 36bhp at 7000 a specially developed two into one exhaust system, we got as much as 39 horsepower at 7000. It was a most exciting machine to ride, as you accelerated it went on a normal power curve, then suddenly the exhaust note would change and it would 'yowl' right on up to maximum about 107mph Back in 1953 on low octane petrol this was quite an exciting performance on the road. Charlie and I enjoyed that engine.
The so-called Star Twin camshaft was a sporty one designed I think by Jack Amott although the design office never gave him credit for it. It was quite useable on the road with silencers fitted and also useful with open pipes. The fellows in my shop told me Jack did all the work on cams and I have no reason to doubt their words. Later on we went to the Daytona camshaft which was really a race cam and not very good at low revs but good at high speeds. Amott did design a racing cam for the twin, but we were unable to make it work properly, it was too radical and hard on valve springs. Reg Wilkes mentioned that if the drawing office had stuck to Jack’s original design they would have been all right. I asked to see Amott's original design and Reg got his camshaft out of a cabinet and showed it to me. It had a much larger base circle than the drawing office version, although to be quite honest I could not see what effect this would have. Wilkes suggested I try it sometime, he was sure it would work better and it did. It was still pretty radical. I never could understand why the drawing office decided to change the base circle diameter. One of the disadvantages of a larger base circle is a higher rubbing speed on the other hand you can get a smoother easier ???
Twin camshaft problems. Whilst working at BSA Dennis Lashmar carried on racing my old 'Pike BSA' with the alloy twin engine. I think he had one good win on a wet day at Snetterton, when it ran cool enough not to blow up. Latterly whenever we went to Silverstone or anywhere to watch him, he finished up sliding along on his backside at about 100mph with a broken crankshaft. This was too dangerous I considered. Once just after the massed start at Silverstone, with the pack all bunched up and approaching Woodcote corner at over 100mph the Beesa suddenly seized and he was sliding along with bikes all round him! I told Mr Hopwood that if we could not do something about the crankshaft breakages we should drop the racing twin. He pointed out that as far as Lashmar was concerned it was his own bike and he could do what he liked with it, but the policy of the factory was to make a twin. I felt we should make a new crank for it to which he agreed and wanted to know if I had any suggestions. By this time Group Research were in the picture at BSA and they demonstrated to me in ten minutes what I had suspected for years. They came up with some very good ideas. One was that the crank needed larger crankpin journals .which would make it stiffer and get away from the frequency at which it now vibrated. Mr Hopwood agreed that their suggestions were fine for 1955 but at that time we had to use what we had. He was interested to know if any other suggestions and Group Research said to put a rolled radius around the ends of each crankpin. They demonstrated by putting a standard crankshaft on vee blocks over the Back to top of the electro-magnetic vibrator they had built.
Then started some sort of motor generator. The noise was like standing next to a jet engine at the airport, it went into a scream and from a scream to an outer pitch sound, onto another phase even higher, then they brought in the electro-magnetic vibrator and the whole place began to buzz. The frequency of the vibrator was adjusted to a multiple of 6,600, the crank vibrated with a high speed buzz, inside ten minutes there was a loud bang, the crank fell in two parts, broken at the usual point, showing the same sort of fracture that we had experienced after three hours running at 6600 RPM. It was a much quicker way of testing a crankshaft and without wrecking an engine. Next they set up one of their special cranks, with the rolled filet radius on the crankpin, it was subjected to the same test, buzzing away on the vee blocks, ten minutes passed, thirty minutes and it was still in one piece. I got tired of waiting and asked to be informed when it broke. It did not break and after one hour it was still good. I was very impressed and so was Mr Hopwood but the factory again did not seem interested, perhaps they could not believe it. This rolling process consisted of applying a ball ended tool to the radius under high pressure in a big lathe.
A few cranks were made, some for research, some for use on the dyno. It seemed fantastic that this simple process could make such a difference. Many years later when I was working for Volkwagen in the USA. I discovered that they cured a rash of broken crankshafts on the 1965 truck engine by the same procedure, except that they did not use a ball, but a small roller to form the radius. It cured the problem for Volkswagen.
Twin engines for Formula 3 We made a number of A7 race engines for this small race class in 1953. They were set up to run on alcohol fuel but were not very reliable and although we got close on 50bhp were repeatedly beaten by Norton singles doing far less. We actually 'borrowed' a 500 Norton engine designed for a formula 3 car, it pulled 42bhp but had 39 ft lbs of torgue against our 36 ft lbs. Part of the trouble with our engines was the installation, they did not get enough cooling air and in one case they had a restricted oil supply, using a long small bore hose from the tank to the engine, the sticky Castor oil simply would not flow fast enough. Another problem was at the head to cylinder block joint, there was a tendency when very hot for a slight blow across to the oil drain holes thus pressurising the crankcase, this blew oil out of the crankcase at every possible point. The cure was to fit small hollow dowels into the head and barrel joint, thus rigidly locating the head, and keeping gas pressure out of the crankcase.
The single overhead camshaft A7 In 1952 they were working on a single overhead camshaft 500 twin. It was a handsome engine with alloy head and barrel, fine pitch finning, exhaust pipe held to the head by nuts. The single overhead cam was driven by bevel gears and a shaft running up what would normally be the push rod tunnel, the valves were operated by rockers. Arthur Bridgewood was working on it in great secrecy in a little shop at the end of the test shop, he had to put up with the noise and fumes of engines being tested. At this point in time it gave the same power as the A7 push rod engine and broke crankshafts with equal regularity. The camshaft was lubricated by the rocker feed which was completely inadequate and of course it wore out cams and nd rockers. Doug Hele suggested using a single wide cam as they did on some Ariels. This cured the rapid wear but the performance suffered due to the geometry of the rockers to cams, one rocker being a trailing rocker, the other a leading one this giving different opening diagram for each valve. I personally felt that the engine could have been made to go if I had been given more freedom as I had with the Gold Star and MC4. One problem was excessive oil consumption due to an accumulation of oil in the rocker box which ran down the valve guides. This we cured by using a C11 oil scavenger pump to pump surplus oil direct to the tank. The feed side of the little oil pump was used to squirt oil through 1/16th holes on to the cam lobes, this cured the rocker and cam wear. At this point we needed a stronger crankshaft and a different design of cams to take advantage off the overhead cam arrangement. By this time Mr Hopwood had lost interest in the engine and said he did not think it would ever be any good, so scrap it. I think that’s what finally happened to it.
The A10 was if anything worse than the A7 when it came to vibration and crankshaft breakages because of its longer stroke. Actually most complaints were about the A10. Although the A7 was the one we raced so that we were more intimately involved in its development. BSA brought about their own demise by their attitude to progress. A favourite saying of Mr Leakes was "Don’t let us be pioneers". Back in the dim and distant past they had lost money on a few experimental ideas that had not worked and that had never been forgotten. Nevertheless when you are the biggest motor cycle manufacturer s in the world you have got to do some pioneering if you want to stay on Back to top. You cannot leave it to small firms like Velocette, who introduced foot gear-change, a successful spring frame, eccentric rocker spindles, a production overhead camshaft engine and many other innovations.
Alloy heads for the twins About the beginning of 1954 it was decided to make a production version of the twin with an alloy head, we had made experimental ones before for the racing people. The head had shrunk in valve seats which gave very little trouble but the spark plugs fitted into bronze inserts screwed and pinned into the head, these persisted in coming out when the plug was removed. I persuaded Mr Hopwood to use long reach plugs screwed directly into the aluminium head, this was very satisfactory. At one stage we could not make a decision on which was best, a single inlet port and one carburettor or twin ports and two carburettors, on the dyno there was very little in it. The first of the Star twins had twin port heads with detachable manifold, it could be used with either one or two carburettors. In point of fact the difference in power is only worth while when running on open pipes. Twin carbs and their cables have to be carefully adjusted to keep both cylinders pulling equally at small throttle openings and just off idling, which is a nuisance to the rider at best, assuming he can cope with the bit of DIY mechanical skill necessary.
After a year we had improved the port configuration and it ran so much better with one big carb that the twin carb option was dropped. We had found it useful to measure the capacity of the inlet ports and check on performance, about 142 to 150cc's gave optimum results. If an engine was down for power we often found the ports undersize. Like all aluminium cylinder heads, these expanded a lot with heads and at the outset we experienced stretched or broken head bolts. These bolts went downwards through the head into the iron cylinder block and would usually break at the root of the last thread, which was the weakest point because it took all the stretching. To overcome this we quite simply put the bolts in a lathe and reducing the diameter of the pIain portion to 10% less than the diameter of the root of the thread. This meant that the thread was no longer the weakest point and that the plain portion could stretch without exceeding its elastic limit.
This was completely successful on the first attempt and no more trouble was experienced with the bolts. They could stretch when the head expanded and return to their original length as the head cooled own. When the new twins were going into production however, Alan Jones who was Works Manager at that time phoned me to say they were unable to make the head bolt as needed, despite my pointing out that we bad found them necessary, he just continued to say they were unable to make them. I went on with my work and forgot about the matter, but I did not have to wait long, within a few hours the motor cycle test shop foreman was on the phone to me complaining the head bolts of the new twins were breaking right and left, so I referred him to Alan Jones. Mr Jones reiterated they were unable to make the bolts we had designed. Prior to this last call I had taken the precaution of calling the drawing office to say that Jones would not follow their drawings of the bolt thus securing an ally. Alan Jones got no sympathy when he had to pull all the bikes concerned back, dismantle the engines and use the bolt we had specified.
Roland Pike Autobiography - Chapter 21
Of 250cc Gold Stars
During 1953 a Mr Thorpe persuaded Bert Perrigo that he should allow us to build a 250 Gold Star on a one off basis and a promise not to worry us for special tuning or special parts. I was quite keen to do this having always been interested in the 250 class. We had one of the experimental small valve scrambler heads left over and an experimental short 6" steel connecting rod, also a special pair of flywheels with crankpin holes specially machined to give 63 mm stroke. The crankpin was special for these short stroke flywheels in that the roller bearing in the centre was standard but the portion that fitted in the flywheels was smaller than usual, being 1.00" diameter and 0.00l taper giving a press fit, the nuts just keeping things together. With this very short stroke there was not room for the standard crankpin nuts. We made special long round nuts with a protruding hexagonal head these were cut off close to the pin after tightening. To remove them they were split with a chisel.
A standard 71mm bore piston and cylinder was used, suitably shortened. Alloy tubular pushrods were used, with lightened tappets, eccentric rocker spindles were used. After experimenting with several cams 22bhp was attained at 7000 – 7600RPM. The engine did not give as much power as the MC4 and it is quite likely that with further running the power increased but it proved very reliable and Mr Thorpe ran it for some years. Later on we built another Gold Star 250, this time using a one-piece crankshaft with outside flywheel and a Sunbeam S7 connecting rod with plain big end. This engine had a 1953 350 Gold Star head and cylinder barrel, the cylinder had to be shortened considerably only seven fins remaining. After quite a small amount of running 26.2bhp was obtained, then the inlet valve broke which ruined the head. When the engine was rebuilt a late type big fin cylinder head was used, a different cylinder head holding down arrangement was used, short steel tubes screwed into the crankcase, bolts fitted from the Back to top screwing into tubes, only four were used and we had no head blowing.
This was the final arrangement of our 250 Gold Star, it proved very successful, the best power recorded being 29.6 at 8250. It would run up to 9000 RPM quite reliably. The inlet port was a pressed in piece of alloy machined after fitting which gave a very straight port. Several engines were built to this design, one was a 350cc, using an 85 mm 500 Gold Star piston on a 61.5 stroke, this was later converted to a 250 by fitting a 72 mm Gold Star piston and was used in the Geoff Monty Special (GMS) for several years. Obviously these 250's were what could best be called ‘codge-ups' using 500 style crankcases for lack of a proper one, the cylinder heads being from 350s had unsuitable valve angles and sizes, the compression ratios were restricted, because of wide angle valves. In spite of these disadvantages proved in the GMS that this was the way to go. The lessons learnt from the ill-fated MC1 were not forgotten. The 250 Gold Star engine in a 500 Gold Star frame was timed at MIRA to do 108mph. In the GMS with some fairing it reached 115mph.
During 1953 a Mr Thorpe persuaded Bert Perrigo that he should allow us to build a 250 Gold Star on a one off basis and a promise not to worry us for special tuning or special parts. I was quite keen to do this having always been interested in the 250 class. We had one of the experimental small valve scrambler heads left over and an experimental short 6" steel connecting rod, also a special pair of flywheels with crankpin holes specially machined to give 63 mm stroke. The crankpin was special for these short stroke flywheels in that the roller bearing in the centre was standard but the portion that fitted in the flywheels was smaller than usual, being 1.00" diameter and 0.00l taper giving a press fit, the nuts just keeping things together. With this very short stroke there was not room for the standard crankpin nuts. We made special long round nuts with a protruding hexagonal head these were cut off close to the pin after tightening. To remove them they were split with a chisel.
A standard 71mm bore piston and cylinder was used, suitably shortened. Alloy tubular pushrods were used, with lightened tappets, eccentric rocker spindles were used. After experimenting with several cams 22bhp was attained at 7000 – 7600RPM. The engine did not give as much power as the MC4 and it is quite likely that with further running the power increased but it proved very reliable and Mr Thorpe ran it for some years. Later on we built another Gold Star 250, this time using a one-piece crankshaft with outside flywheel and a Sunbeam S7 connecting rod with plain big end. This engine had a 1953 350 Gold Star head and cylinder barrel, the cylinder had to be shortened considerably only seven fins remaining. After quite a small amount of running 26.2bhp was obtained, then the inlet valve broke which ruined the head. When the engine was rebuilt a late type big fin cylinder head was used, a different cylinder head holding down arrangement was used, short steel tubes screwed into the crankcase, bolts fitted from the Back to top screwing into tubes, only four were used and we had no head blowing.
This was the final arrangement of our 250 Gold Star, it proved very successful, the best power recorded being 29.6 at 8250. It would run up to 9000 RPM quite reliably. The inlet port was a pressed in piece of alloy machined after fitting which gave a very straight port. Several engines were built to this design, one was a 350cc, using an 85 mm 500 Gold Star piston on a 61.5 stroke, this was later converted to a 250 by fitting a 72 mm Gold Star piston and was used in the Geoff Monty Special (GMS) for several years. Obviously these 250's were what could best be called ‘codge-ups' using 500 style crankcases for lack of a proper one, the cylinder heads being from 350s had unsuitable valve angles and sizes, the compression ratios were restricted, because of wide angle valves. In spite of these disadvantages proved in the GMS that this was the way to go. The lessons learnt from the ill-fated MC1 were not forgotten. The 250 Gold Star engine in a 500 Gold Star frame was timed at MIRA to do 108mph. In the GMS with some fairing it reached 115mph.
Roland Pike Autobiography - Chapter 20
Tales of the Bantam C12, C15 & MC4
The BSA Bantam and the Harley Davidson Hummer were snatched from the Germans as 'reparations' after World War II. The Bantam started as a DKW in 1935 or 36 when it was considered modern with its flat Back to top piston, but by 1946 when BSA got it, it was already old fashioned. One could get about 4.5bhp from the 125cc if you were lucky, more often only about 3.5. The noise they made was dreadful and so was the oil they blew all over the test shop. We worked on them for a couple of years, making all sorts of experimental bits and pieces, none of which worked very well. I recall someone wanted to ride one in the International Six Days Trial and Bert Perrigo the BSA Competition manager persuaded us to build him a 'special'.
Reg Wilkes worked on it for a couple of weeks and got 5 or 6bhp over a wider range than the standard machine. Another time an Australian sent us under great secrecy his Bantam which was reputed to be very powerful and high revving and all the rest. It was highly modified and ran on alcohol blended fuel, they claimed 12bhp and had been timed to exceed 90mph We were suitably impressed and set it up on our dyno, we mixed the prescribed blend of fuel of alcohol benzole and acetone and ran it. However we could not stop it from four stroking and it would not give more than 6bhp. We were reluctant to jet it down in case we burned it up. So we gave up, deciding that the cold damp November air did not suit it, it apparently needed hot dry Aussie air.
In the development shop at BSA we used to hate the sound and sight of the Bantam. When I first went there we were responsible for Bantam development, but I disliked two strokes then and I still do. I suggested to Hopwood why didn’t he get Herman Meier who had been with on the Continental Circus trip in 1951 who was an enthusiast as I felt sure he would make them run. Finally after a lot of trouble with work permits and so on we got Herman over and he shared an office with me. He doubled the power of the Bantam in a few months. Unfortunately Herman was a temperamental type and I eventually recommended that he be moved to Redditch where the Bantams were made anyway. Here he got some good power outputs from the 125cc Bantam and developed the larger versions they eventually produced.
Occasionally a 250 C12 came into the shop, this was a simple and cheap engine, designed in 1935 as a light and inexpensive utility machine based on a Blackburn design used by Excelsior and Frances Barnett a year or earlier. It was novel in that the push rods crossed in the tunnel at the same angle as the valves.
One day the C12 production line was stopped due to repeated complaints from the Dealers of 'knock' from the engine. Mr Leake called a meeting of everyone concerned and told us to cure it or it would have to be dropped from production. A big panic ensued, several engines that were 'knockers' were brought into my shop and we found the in some cases the knock could be cured by retarding the ignition very slightly, but some of the worst examples 'knocked' regardless of timing etc. These were stripped right down for thorough examination, we noticed that the flywheels were made of cast iron whereas when the engine was first produced it had flywheels of steel stampings. We were able to get some of these and when fitted to the worst offenders it completely cured the problem. Whilst fiddling with C12 250cc we tried the alloy cylinder head from the Ariel Colt, a 200cc version of the same engine, this cylinder head cured 'knocking' and gave more power, which prompted us to make a 'deluxe' C12 which after a few quite simple modifications gave 15bhp. An engine was passed to the experimental dept for road testing, but I do not remember any conclusions being made and soon after the 015 was designed. This was another 'cheap' design based on the Triumph Terrier 150cc. In my opinion a poor thing.
The MC4 design which was very promising was essentially half an A7 twin, the better half I thought as it was more reliable than the A7. It was intended to make a 350cc version using A10 parts. This would have been helpful to the production people as so many parts would have been interchangeable. The camshaft had to be different of course for a single cylinder. The original design used a one-piece iron casting unfortunately the cast iron was not up to the job and the first one broke, possibly 'Nodular' iron would have done the trick or the larger crankpin as used later in A7 & A10 would have helped. At about this time (1952) we used our first alternators built into the engine timing case, this gave it an odd shaped bulge, they worked very well and used less horsepower than the regular generator with rotating armature. I think if it had gone into production some resistance would have been encountered from the typical motor cyclist over the odd appearance of this engine, but once they realised the advantages of the engine they would soon forget the appearance.
The MC4 gave half the power of the racing A7 but with much greater reliability. This could only be explained by the fact that the main bearings were only some three inches apart giving an inherently more rigid lower end than the A7, which suffered from crankshaft whip. One of the things we learned a lot about during the MC4 development was mechanical berathers. As designed it had a disc valve breather as on the earlier Gold Star, at high revolutions the little pen steel disc valve could not cope and as a result blew oil out in large amounts. The same problem on the early Gold Star caused several retirements in the Clubmans TT races due to loss of oil and too much oil on the rear tire became very mechanical breather conscious and tried to adapt the A7 mechanical breather to the MC4. At first it would not work satisfactorily finally we fitted copper pipe inside the crankcase, picking up breather air from a 'dry' spot in the corner of the crankcase. This was much more effective in terms of oil loss, but the crankcase pressure was disappointing until we retarded the timing of the breather valve by 70 degrees, it would then maintain a pressure inside the crankcase of between of 4 and 7 inches of water lower than atmospheric at all speeds. This kept the engine very clean, even when belting round MonthIery track at nearly 100mph.
Due to the MIRA test track not being completed we arranged to go to France and use the banked track at Monthlery for a week. We.loaded the MC4, a 350 Gold Star and two 650 A10 Police Specials into our van, which was my old race van which I had bought from Ray Amm in 1952, now fitted' with a V8 engine. Charlie Salt and I were the hobbledeboys, we drove the van via Dover and Boulogne to Paris. Arthur Lupton and Bert Hopwood drove an A40 Austin. Bill Nichols flew out to join us a little later. Strangely enough although Bill was such a dare-devil in Scrambles and on the road, he was completely over-awed by the banked track. He was unable to lap as fast as I did and I was putting on weight and my leathers were tight. Charlie being neat and slim lapped about 3mph faster than I did and I was a little faster than Bill. The demonstration of the police bikes to the National Guard was the funniest thing. The police were all Triumph enthusiasts and did not like BSAs. When our bikes lapped faster than the Police Triumphs they removed the silencers, saying "now we will go faster". We wondered whether we should remove our silencers as well and go faster still, but it was getting ridiculous. Their police model Triumph had the infamous sprung hub and at speed on the banking looked positively dangerous. It started to drizzle with rain and I thought now we will show them, our bikes had the old plunger springing, it seemed steadier than the Triumph on the banking. However they would not ride on the track in the wet. I did a couple of fast laps in the wet at about 103mph and was skating about all over the place. So we adjourned for lunch with the Distributor and his guests from the Guard Nationale. We spent the rest of our time there testing the MC4 and found the heavy front mudguards were holding our speed down to 93mph, so we removed front mudguard and tipped the headlamp to try and improve the streamlining - we could not remove jt because it contained switchgear etc. The bike was road equipped except for a megaphone in place of the silencer. This put the speed up to 96 for the lap. When timed the Gold Star and Charlie slipstreamed me on the MC4 we lapped at just on 99mph. When we switched bikes we could lap at 97. For a 250cc push rod machine which was not designed as a racer these times were very good, the engine was putting out about 24.5bhp. The racing Excelsior 250 claimed 22.5bhp on 50/50 petrol benzole. We were using pump fuel of 78 octane. However when we returned to the factory the Board of Directors decided against producing the MC4 which was a great disappointment to all of us, we who had seen its promise. A version was assembled with sheet metal covering over crankcase and gearbox, a different colour scheme and Sunbeam name on the tank, this was also turned, down. The C12 and its variations stayed in production.
The BSA Bantam and the Harley Davidson Hummer were snatched from the Germans as 'reparations' after World War II. The Bantam started as a DKW in 1935 or 36 when it was considered modern with its flat Back to top piston, but by 1946 when BSA got it, it was already old fashioned. One could get about 4.5bhp from the 125cc if you were lucky, more often only about 3.5. The noise they made was dreadful and so was the oil they blew all over the test shop. We worked on them for a couple of years, making all sorts of experimental bits and pieces, none of which worked very well. I recall someone wanted to ride one in the International Six Days Trial and Bert Perrigo the BSA Competition manager persuaded us to build him a 'special'.
Reg Wilkes worked on it for a couple of weeks and got 5 or 6bhp over a wider range than the standard machine. Another time an Australian sent us under great secrecy his Bantam which was reputed to be very powerful and high revving and all the rest. It was highly modified and ran on alcohol blended fuel, they claimed 12bhp and had been timed to exceed 90mph We were suitably impressed and set it up on our dyno, we mixed the prescribed blend of fuel of alcohol benzole and acetone and ran it. However we could not stop it from four stroking and it would not give more than 6bhp. We were reluctant to jet it down in case we burned it up. So we gave up, deciding that the cold damp November air did not suit it, it apparently needed hot dry Aussie air.
In the development shop at BSA we used to hate the sound and sight of the Bantam. When I first went there we were responsible for Bantam development, but I disliked two strokes then and I still do. I suggested to Hopwood why didn’t he get Herman Meier who had been with on the Continental Circus trip in 1951 who was an enthusiast as I felt sure he would make them run. Finally after a lot of trouble with work permits and so on we got Herman over and he shared an office with me. He doubled the power of the Bantam in a few months. Unfortunately Herman was a temperamental type and I eventually recommended that he be moved to Redditch where the Bantams were made anyway. Here he got some good power outputs from the 125cc Bantam and developed the larger versions they eventually produced.
Occasionally a 250 C12 came into the shop, this was a simple and cheap engine, designed in 1935 as a light and inexpensive utility machine based on a Blackburn design used by Excelsior and Frances Barnett a year or earlier. It was novel in that the push rods crossed in the tunnel at the same angle as the valves.
One day the C12 production line was stopped due to repeated complaints from the Dealers of 'knock' from the engine. Mr Leake called a meeting of everyone concerned and told us to cure it or it would have to be dropped from production. A big panic ensued, several engines that were 'knockers' were brought into my shop and we found the in some cases the knock could be cured by retarding the ignition very slightly, but some of the worst examples 'knocked' regardless of timing etc. These were stripped right down for thorough examination, we noticed that the flywheels were made of cast iron whereas when the engine was first produced it had flywheels of steel stampings. We were able to get some of these and when fitted to the worst offenders it completely cured the problem. Whilst fiddling with C12 250cc we tried the alloy cylinder head from the Ariel Colt, a 200cc version of the same engine, this cylinder head cured 'knocking' and gave more power, which prompted us to make a 'deluxe' C12 which after a few quite simple modifications gave 15bhp. An engine was passed to the experimental dept for road testing, but I do not remember any conclusions being made and soon after the 015 was designed. This was another 'cheap' design based on the Triumph Terrier 150cc. In my opinion a poor thing.
The MC4 design which was very promising was essentially half an A7 twin, the better half I thought as it was more reliable than the A7. It was intended to make a 350cc version using A10 parts. This would have been helpful to the production people as so many parts would have been interchangeable. The camshaft had to be different of course for a single cylinder. The original design used a one-piece iron casting unfortunately the cast iron was not up to the job and the first one broke, possibly 'Nodular' iron would have done the trick or the larger crankpin as used later in A7 & A10 would have helped. At about this time (1952) we used our first alternators built into the engine timing case, this gave it an odd shaped bulge, they worked very well and used less horsepower than the regular generator with rotating armature. I think if it had gone into production some resistance would have been encountered from the typical motor cyclist over the odd appearance of this engine, but once they realised the advantages of the engine they would soon forget the appearance.
The MC4 gave half the power of the racing A7 but with much greater reliability. This could only be explained by the fact that the main bearings were only some three inches apart giving an inherently more rigid lower end than the A7, which suffered from crankshaft whip. One of the things we learned a lot about during the MC4 development was mechanical berathers. As designed it had a disc valve breather as on the earlier Gold Star, at high revolutions the little pen steel disc valve could not cope and as a result blew oil out in large amounts. The same problem on the early Gold Star caused several retirements in the Clubmans TT races due to loss of oil and too much oil on the rear tire became very mechanical breather conscious and tried to adapt the A7 mechanical breather to the MC4. At first it would not work satisfactorily finally we fitted copper pipe inside the crankcase, picking up breather air from a 'dry' spot in the corner of the crankcase. This was much more effective in terms of oil loss, but the crankcase pressure was disappointing until we retarded the timing of the breather valve by 70 degrees, it would then maintain a pressure inside the crankcase of between of 4 and 7 inches of water lower than atmospheric at all speeds. This kept the engine very clean, even when belting round MonthIery track at nearly 100mph.
Due to the MIRA test track not being completed we arranged to go to France and use the banked track at Monthlery for a week. We.loaded the MC4, a 350 Gold Star and two 650 A10 Police Specials into our van, which was my old race van which I had bought from Ray Amm in 1952, now fitted' with a V8 engine. Charlie Salt and I were the hobbledeboys, we drove the van via Dover and Boulogne to Paris. Arthur Lupton and Bert Hopwood drove an A40 Austin. Bill Nichols flew out to join us a little later. Strangely enough although Bill was such a dare-devil in Scrambles and on the road, he was completely over-awed by the banked track. He was unable to lap as fast as I did and I was putting on weight and my leathers were tight. Charlie being neat and slim lapped about 3mph faster than I did and I was a little faster than Bill. The demonstration of the police bikes to the National Guard was the funniest thing. The police were all Triumph enthusiasts and did not like BSAs. When our bikes lapped faster than the Police Triumphs they removed the silencers, saying "now we will go faster". We wondered whether we should remove our silencers as well and go faster still, but it was getting ridiculous. Their police model Triumph had the infamous sprung hub and at speed on the banking looked positively dangerous. It started to drizzle with rain and I thought now we will show them, our bikes had the old plunger springing, it seemed steadier than the Triumph on the banking. However they would not ride on the track in the wet. I did a couple of fast laps in the wet at about 103mph and was skating about all over the place. So we adjourned for lunch with the Distributor and his guests from the Guard Nationale. We spent the rest of our time there testing the MC4 and found the heavy front mudguards were holding our speed down to 93mph, so we removed front mudguard and tipped the headlamp to try and improve the streamlining - we could not remove jt because it contained switchgear etc. The bike was road equipped except for a megaphone in place of the silencer. This put the speed up to 96 for the lap. When timed the Gold Star and Charlie slipstreamed me on the MC4 we lapped at just on 99mph. When we switched bikes we could lap at 97. For a 250cc push rod machine which was not designed as a racer these times were very good, the engine was putting out about 24.5bhp. The racing Excelsior 250 claimed 22.5bhp on 50/50 petrol benzole. We were using pump fuel of 78 octane. However when we returned to the factory the Board of Directors decided against producing the MC4 which was a great disappointment to all of us, we who had seen its promise. A version was assembled with sheet metal covering over crankcase and gearbox, a different colour scheme and Sunbeam name on the tank, this was also turned, down. The C12 and its variations stayed in production.
Saturday 24 January 2009
Roland Pike Autobiography - Chapter 19
The Importance of the Export Market
After the war Sir Stafford Cripps devalued the pound sterling to help Britain compete in the export markets, but unfortunately few businessmen appreciated the value of exports. I did not realise it myself until I was sent to America by BSA, then I realised Britain needed dollars to buy food, raw materials and fuel and to get them we had to export. To export you have got to give the customer what they want and that is what I tried to do at BSA. To be sure, Mr Rawson their Export Manager and Mr Leake were aware of the need for exports, but it was on the factory floor that this was not appreciated. Anything special was a nuisance it was an uphill job. I was not high-up enough to carry any weight.
Bert Hopwood and Bert Perrigo understood and did what they could and Mr Leake managed to give the Americans what they wanted. BSA had two representatives in the United States, Hap Alzina on the West coast and Alf Child of Rich Child Cycle company on the East. Alf Child was a great promoter, no doubt about it, but unfortunately he did not understand motor cycles as well as Hap Alzina. Mr Childs depended on others for the technical or specialised advice so that some of the information he gave us was not always good. As a result a lot of what he told us was disregarded, good or bad. Hap Alzina was just the opposite and was a pillar of strength, supporting the design and technical depts wherever he could. He was able to pull strings with the AMA that Alf Child could never do.
Alf Childs was British, born in Nutley, Sussex, UK. He ran away to sea when he was only 14. He had lost an arm and was known inevitably as the 'one-armed bandit' in New Jersey. He was a flamboyant character and often rude to people, but once you got to know him was very likeable. At first you could be very put off by him as he had a habit of being abusive and used the most crude language, not just about things but personal with it. At that time I did not understand his attitude and took offense. I intimated to Mr Leake that I did not want to visit Alf Child in the US anymore.
Finally Mr Leake found out my complaint and gave Alf Child a dressing down. I was sent back to America in 1953 for Daytona, during this visit I listened carefully to what the Dealers, their riders, Tommy McDermott, Warren Sherwood, Gene Thiessen and Al Gunter had to say and went back to the factory and explained to them that BSA had to produce a bike entirely for the American competition market. As a result I was given the go ahead to produce a prototype. I used one of Bill Nicholson’s production trials frames, welded light and rigid. The Dealers in America had said Daytona is only one race a year and we were putting everything into it, what would they do with the bikes afterwards? They were no good for the half-mile as they were too heavy, they wanted something light. So I decided that they could get something light and produced a prototype that weighed 276lbs by using a lot of light alloys, fitted with a Gold Star engine, it would do 114mph on the timing strip, mean speed.
The twin engine in the meantime had been developed to give more power and reliability using an alloy head and a hot cam, the power was available from about 5250 to 7250 RPM, but it was not so tractable as the single although it gave more power and was 2mph faster on the timing strip. Running side by side the single would reach the end of the timing strip first, although finishing the measured mile at a lower speed. We went to Daytona in 1954 with eight rigid frame lightweight racers, four with singles and four twins. Alf Childs wanted an extra bike for Bobby Hill, all we had available was a 500cc twin in a Clubmans type spring frame, ironically this was the winning machine! We collected five of first eight places, the best BSA ever did at Daytona.
The AMA at this time were very strict with compression ratios, the maximum allowed was 8:1, we were allowed 1 mm oversize pistons, so naturally all these bikes had the extra few cc capacity (508cc) and it did give a wee bit more power. BSA made 100 of these rigid frame, short track machines and some were still being raced on half mile and mile circuits twenty three years later. Later on the AMA allowed up to 9:1 compression ratio, which was more helpful to the twins than the singles. By 1958 the factory was not giving much support to the American racers. I remember we had difficulty in obtaining Nirnonic 80 valves in the US. Nimonic 80 is made by Henry Wiggins in the UK and should be readily available. A similar material is available in the States under a similar name.
An overhead valve engine running at high speed presents a difficult problem for the valves due to the weight of the push rods, tappets and rockers the valve springs have to be fairly powerful which in turn puts a load on the valves, particularly the exhaust valve which runs at bright red heat. A Gold Star running under full load and full throttle can demonstrate this, just look into the carburettor intake, a small segment of the exhaust valve is visible glowing red hot . The British motorcycle industry was at its peak of success in the days when people rode their motor cycles to work as well as for pleasure, owning a car was not so affordable then and the bike was much more convenient than bus, train or tram.
I think motor cycles are a viable solution to the future need for low cost transportation and with ever increasing costs of fuel. The bike takes up less room on our crowded highways. The utility bike of the future may well be a 250 single or a 350 twin, these could easily give 80 mpg, US or imperial! Bikes for Class 'C' Racing. When I first had anything to do with Class 'C', we felt very restricted due to the strict regulations. 8:1 compression ratio, kick- starters etc. Any competitor in a race could claim the winners bike on payment of $1500. This was to discourage excessive investment of money and time into a certain machine by the factory or dealer, and to ensure that all the race bikes were reasonably equal in performance. In other words a no-hope rider could theoretically buy himself the best machine at a race by simply claiming it. In practice this did not happen too often because anyone who did this would be regarded as un-sporting. I heard of a case where a bike was claimed and the factory concerned bought the would-be purchaser off by offering him more money not to claim it. Any special machines had to be approved by the AMA and at least 100 produced for sale to dealers. In 1953 we had got into quite an argument over this rule. BSA claimed the 1953 racer was a Star Twin with a few modifications that were available to the public. The AMA did not agree and told us we had to make a 100. Since we had not had any good results with the model, we knew we would never sell a 100 of them and finally made about 40 or so.
I remember Fron Purslow bought one and tried to race it in England on short circuits, with no success. One of the friendliest racers I met at Daytona was Al Gunter in 1953 and last saw him at Daytona in 1958 by which time he was a changed man. He had been terribly mutilated in various crashes although you saw flashes of the old Al Gunter in the smile and enthusiasm. He had tried to make a career out of motor cycle racing in the 50's, this was difficult and as he got older had to compete with many up and coming younger riders. Eventually he was confined to a wheelchair and in 1976 we heard of his suicide. Al Gunter had been a very enthusiastic racer of BSA's and co-operated a great deal in our experiments. In the mid '50's he was one of the fastest BSA men in the USA. The last time I talked with him, Al said he was getting over 50bhp at the back wheel of his Gold Star racer at 8000 RPM.
Harman and Collins helped him in these experiments, using special cams and special push rods to aid higher revving. At 8000 RPM I did not expect a Gold Star to last very long, which Al confirmed and said the motor was only good for a short track. Dick Mann another BSA rider who was riding Harley Davidson at Daytona in 1958. One time he handed me a factory racing Harley 45 cu. inch, flathead twin and asked if I had ever had a ride on one. I had not and he suggested I have a go. This was in front of all the Harley people and their eyes were popping out. Before anyone could stop me I hopped on and a rushed up the beach. It was fantastic and felt like a Manx Norton. It steered well, brakes were good, the motor pulled hard to 7400 RPM, then the power dropped right off and you went to the next gear. Torque was strong all the way. I don't know how our BSA riders ever competed with them.
Gold Stars that were raced on other US tracks got a certain amount help from the Distributors but the factory support was very limited. S&W valve springs came to our attention through Hap Alzina, he thought they might help the twins, they certainly did and Gold Star singles as well. We had tremendous success with them. According to theory they should not work! But then, theory says the Bumble Bee cannot fly.
After the war Sir Stafford Cripps devalued the pound sterling to help Britain compete in the export markets, but unfortunately few businessmen appreciated the value of exports. I did not realise it myself until I was sent to America by BSA, then I realised Britain needed dollars to buy food, raw materials and fuel and to get them we had to export. To export you have got to give the customer what they want and that is what I tried to do at BSA. To be sure, Mr Rawson their Export Manager and Mr Leake were aware of the need for exports, but it was on the factory floor that this was not appreciated. Anything special was a nuisance it was an uphill job. I was not high-up enough to carry any weight.
Bert Hopwood and Bert Perrigo understood and did what they could and Mr Leake managed to give the Americans what they wanted. BSA had two representatives in the United States, Hap Alzina on the West coast and Alf Child of Rich Child Cycle company on the East. Alf Child was a great promoter, no doubt about it, but unfortunately he did not understand motor cycles as well as Hap Alzina. Mr Childs depended on others for the technical or specialised advice so that some of the information he gave us was not always good. As a result a lot of what he told us was disregarded, good or bad. Hap Alzina was just the opposite and was a pillar of strength, supporting the design and technical depts wherever he could. He was able to pull strings with the AMA that Alf Child could never do.
Alf Childs was British, born in Nutley, Sussex, UK. He ran away to sea when he was only 14. He had lost an arm and was known inevitably as the 'one-armed bandit' in New Jersey. He was a flamboyant character and often rude to people, but once you got to know him was very likeable. At first you could be very put off by him as he had a habit of being abusive and used the most crude language, not just about things but personal with it. At that time I did not understand his attitude and took offense. I intimated to Mr Leake that I did not want to visit Alf Child in the US anymore.
Finally Mr Leake found out my complaint and gave Alf Child a dressing down. I was sent back to America in 1953 for Daytona, during this visit I listened carefully to what the Dealers, their riders, Tommy McDermott, Warren Sherwood, Gene Thiessen and Al Gunter had to say and went back to the factory and explained to them that BSA had to produce a bike entirely for the American competition market. As a result I was given the go ahead to produce a prototype. I used one of Bill Nicholson’s production trials frames, welded light and rigid. The Dealers in America had said Daytona is only one race a year and we were putting everything into it, what would they do with the bikes afterwards? They were no good for the half-mile as they were too heavy, they wanted something light. So I decided that they could get something light and produced a prototype that weighed 276lbs by using a lot of light alloys, fitted with a Gold Star engine, it would do 114mph on the timing strip, mean speed.
The twin engine in the meantime had been developed to give more power and reliability using an alloy head and a hot cam, the power was available from about 5250 to 7250 RPM, but it was not so tractable as the single although it gave more power and was 2mph faster on the timing strip. Running side by side the single would reach the end of the timing strip first, although finishing the measured mile at a lower speed. We went to Daytona in 1954 with eight rigid frame lightweight racers, four with singles and four twins. Alf Childs wanted an extra bike for Bobby Hill, all we had available was a 500cc twin in a Clubmans type spring frame, ironically this was the winning machine! We collected five of first eight places, the best BSA ever did at Daytona.
The AMA at this time were very strict with compression ratios, the maximum allowed was 8:1, we were allowed 1 mm oversize pistons, so naturally all these bikes had the extra few cc capacity (508cc) and it did give a wee bit more power. BSA made 100 of these rigid frame, short track machines and some were still being raced on half mile and mile circuits twenty three years later. Later on the AMA allowed up to 9:1 compression ratio, which was more helpful to the twins than the singles. By 1958 the factory was not giving much support to the American racers. I remember we had difficulty in obtaining Nirnonic 80 valves in the US. Nimonic 80 is made by Henry Wiggins in the UK and should be readily available. A similar material is available in the States under a similar name.
An overhead valve engine running at high speed presents a difficult problem for the valves due to the weight of the push rods, tappets and rockers the valve springs have to be fairly powerful which in turn puts a load on the valves, particularly the exhaust valve which runs at bright red heat. A Gold Star running under full load and full throttle can demonstrate this, just look into the carburettor intake, a small segment of the exhaust valve is visible glowing red hot . The British motorcycle industry was at its peak of success in the days when people rode their motor cycles to work as well as for pleasure, owning a car was not so affordable then and the bike was much more convenient than bus, train or tram.
I think motor cycles are a viable solution to the future need for low cost transportation and with ever increasing costs of fuel. The bike takes up less room on our crowded highways. The utility bike of the future may well be a 250 single or a 350 twin, these could easily give 80 mpg, US or imperial! Bikes for Class 'C' Racing. When I first had anything to do with Class 'C', we felt very restricted due to the strict regulations. 8:1 compression ratio, kick- starters etc. Any competitor in a race could claim the winners bike on payment of $1500. This was to discourage excessive investment of money and time into a certain machine by the factory or dealer, and to ensure that all the race bikes were reasonably equal in performance. In other words a no-hope rider could theoretically buy himself the best machine at a race by simply claiming it. In practice this did not happen too often because anyone who did this would be regarded as un-sporting. I heard of a case where a bike was claimed and the factory concerned bought the would-be purchaser off by offering him more money not to claim it. Any special machines had to be approved by the AMA and at least 100 produced for sale to dealers. In 1953 we had got into quite an argument over this rule. BSA claimed the 1953 racer was a Star Twin with a few modifications that were available to the public. The AMA did not agree and told us we had to make a 100. Since we had not had any good results with the model, we knew we would never sell a 100 of them and finally made about 40 or so.
I remember Fron Purslow bought one and tried to race it in England on short circuits, with no success. One of the friendliest racers I met at Daytona was Al Gunter in 1953 and last saw him at Daytona in 1958 by which time he was a changed man. He had been terribly mutilated in various crashes although you saw flashes of the old Al Gunter in the smile and enthusiasm. He had tried to make a career out of motor cycle racing in the 50's, this was difficult and as he got older had to compete with many up and coming younger riders. Eventually he was confined to a wheelchair and in 1976 we heard of his suicide. Al Gunter had been a very enthusiastic racer of BSA's and co-operated a great deal in our experiments. In the mid '50's he was one of the fastest BSA men in the USA. The last time I talked with him, Al said he was getting over 50bhp at the back wheel of his Gold Star racer at 8000 RPM.
Harman and Collins helped him in these experiments, using special cams and special push rods to aid higher revving. At 8000 RPM I did not expect a Gold Star to last very long, which Al confirmed and said the motor was only good for a short track. Dick Mann another BSA rider who was riding Harley Davidson at Daytona in 1958. One time he handed me a factory racing Harley 45 cu. inch, flathead twin and asked if I had ever had a ride on one. I had not and he suggested I have a go. This was in front of all the Harley people and their eyes were popping out. Before anyone could stop me I hopped on and a rushed up the beach. It was fantastic and felt like a Manx Norton. It steered well, brakes were good, the motor pulled hard to 7400 RPM, then the power dropped right off and you went to the next gear. Torque was strong all the way. I don't know how our BSA riders ever competed with them.
Gold Stars that were raced on other US tracks got a certain amount help from the Distributors but the factory support was very limited. S&W valve springs came to our attention through Hap Alzina, he thought they might help the twins, they certainly did and Gold Star singles as well. We had tremendous success with them. According to theory they should not work! But then, theory says the Bumble Bee cannot fly.
Tuesday 13 January 2009
Roland Pike Autobiography Chapter 18
The Development Shop and Clubmans TT
The primary aim of my development shop at BSA apart from improving standard machines was to win the Clubmans TT. We were not supposed to be interested in International racing, other than in connection with the MC1 project. The scrambler motor was considered powerful enough. For the Clubmans models we were always searching for a little more speed and of course reliability. This went hand in hand with American class ‘C’ AMA racing, since what was good for the Clubmans was also good for class ‘C’.
BSA did not dominate the early Clubmans 500cc TT races which were won mainly by Triumph and Norton. The 1949 race for 350cc was BSA's first victory. Many BSA 350's were entered and few finished but that year the winner was a BSA.
They had plunger rear suspension, leaked oil, and tended to blow oil out of the engine breather, to the extent of running low on oil, causing seizures etc. Nevertheless, the two or three best BSAs on that occasion did very well, competing against Velocette KSS models and 350 Norton Internationals. In 1952 BSA had hoped to provide a challenge in the 500cc Clubmans with an all alloy twin engine which would be promoted as Gold Star Twin if successful.
However the regulations prevented their use as it was not yet a production model. A few standard A7 500cc twins were built to Clubmans specifications, they pushed out 36-38bhp which was about the same as the production Manx Norton, but in fact were unreliable and had a peaky performance, also did not handle as well as the single. In 1953 it was the same story, the old CB350 did quite well as did the 500cc singles of which there were two or three entered.
The 500cc BSA twins were getting pretty unpopular by that time because when the crankshaft broke, they often destroyed the crankcases and fetched the rider off. If this happens at 100mph it’s pretty scary. Triumphs were still going strong with their 500cc twins although they had their share of blown engines too. They won by the use of specially prepared hand picked machines and some good riders. By 1954 the Gold Star had new heads with big area finning, eccentric rocker spindles, shorter connecting rods, tubular push rods (instead of solid alloy) and Nimonic exhaust valves, a timed crankcase breather (which controlled the tendency to blow oil out on to the road and rear tires) and needle roller bearings on the gearbox layshaft. So far as factory involvement in preparing machines for the Clubmans went there was none, however we used to maintain a workshop in the Island for the benefit of all riders of BSAs. The riders who showed the best in practice might get the benefit of someone like Cyril Halliburn working on their motors. Triumph and Norton did the same thing.
Triumph had Ernie Nott an ex- TT winner working on some of their customers’ bikes. I was in the Island workshop keeping an eye on technical problems and helping Charlie Salt with his TT machines. Before coming to BSA Hopwood had designed the Norton twin, its outstanding feature was the way the cylinder heads were splayed, cut at the front giving better cooling and more fins where needed. This feature was patented, so of course could not be used by BSA.
Nevertheless the new A7 he designed for 1952 was a good rugged engine compared with the earlier BSA twins. It had a weak point in the timing side main bearing and rather small tappets, they wore more rapidly than they should, and also a tendency to vibrate and break crankshafts. We carried out a lot of tests to improve the timing side main bearing trying an all white metal bearing, a copper-lead bearing and a needle roller bearing. This last was far and away the best but required a different oil feed to the crankshaft to lubricate the rod bearings but as the factory did not want to make a change, we continued with the short life main bearing. The crankshaft breakage problem was really due to two things, the diameter of the crankshaft rod bearing journals gave a natural frequency of vibration that coincided with 6,600 & 3,300 RPM, any prolonged full throttle running at 6,600 rpm soon broke the crank adjacent to the rod bearing journal.
A member in the Group Research dept. gave this matter some thought and came up with the answer - a better finish in the fillet radius each side of the big end journal. In production the journal radius was done by the same grinding wheel that ground the journal, this meant that tiny microscopic scratches were left and this is where the fatigue fractures invariably started. His solution was to roll under high pressure a ball around each journal, leaving a perfectly smooth finish.
The layout of the Test shop.There were five Heenan &Froude hydraulic dynamometers and one electric dyno, an elaborate set up ideal for research work. The electric dyno could be reversed to drive the engine you were testing. Everyone was half scared of it, except Arthur Bridgewood, he used it a lot. He insisted that there was always an apprentice standing with his hand on the big knife switch to cut it off dead, if an engine blew up whilst running, current would continue to flow rotating the already damaged engine to destruction. The operator had to be wide awake and act quickly if something broke or seized. We eventually traded this dyno to Research for a nearly new DPX1. The other dynos were two DPX2, one DPX0 and two DPX1. When the MC1 came into the shop we had a new high speed dyno- a DPX3 .
Originally all the dynos were driven by chain from the engine sprocket, a very inefficient method, but simple. We used a 2:1 ratio to keep things simple. Anyone who favours primary chain drive should attend a test using chain drive. At about 6000 RPM take a reading, then get a squirt oil can and oil the chain, the engine will pick up an apparent 2bhp.
Heenan used to recommend a shaft and two universal joints like in a car, but we found them unreliable, the universal joints used to break up and fly all over the shop like shrapnel. We eventually went to a bonded rubber coupling which if lined up carefully gave good results. All the dynamometers were arranged in a line with their axis parallel, very neat, but very impractical, as the blast of cooling air and exhaust blew from one to the next, making it impractical to use more than one engine at a time, due to blast of air and if testing a race engine the noise and fumes, to say nothing of oil.
To try to get away from these difficulties and to control the blowing oil we had some metal shields on castors made which could be rolled around behind the engines. When cooling air blowers were turned on the shields tended to move around, they soon got coated in oil and one had to avoid brushing against the oily surface. This system remained in used for some years until the shop was demolished. The development shop was once a stable, it was quite old, with over 30 foot ceiling and heated by steam pipes. In summer the only cooling was by opening ventilators.
Originally there was no provision for letting air and fumes out, so a rather expensive sheet metal ducting system was built with a 6 hp fan drawing air from just behind each engine. Cooling air was blown over each engine by a powerful 'squirrel cage' blower, giving an 80mph blast. This cooling air was ducted in from the roof and it was possible to select cold outside air or warm inside shop air by operating a flap valve in a ??? WY' joint by means of a cord. When you run an engine under full power on a dyno you have to be wide-awake, if it starts to tighten up or the exhaust note changes you shut it off immediately. If there are two engines running, it is difficult to tell which is about to falter.
There was no objection to running an engine on the shop exhaust system for 'running in' purposes, this running in was an important part of testing a new engine, it will not deliver its best power until it is 'broken in'. Once a month we would take an engine at random from the production line and after a couple of hours of gentle running, take a full power curve, if it was down for power we would strip it to find out why. Should it be badly down on power we would take another engine from the same batch and test it, if it also was bad, we had to get that particular assembly line stopped until the fault could be located and corrected. Needless to say this was an unpopular action, but was necessary to preserve (the factory's reputation.
The only time I can remember actually calling for a halt to production was on the A10 line and later on the C12. Usually what happened was a cumulative effect due to tightness, maybe a worn tool, making one part slightly oversize and a corresponding part slightly undersize. Sometimes an extra hour running on the dyno would be enough to restore the power.
All Gold Stars and Road Rockets were tested by the engine test dept after a period of running in. The cylinder heads and cylinders were removed for inspection and individual power curves issued with each engine. Some BSA production engines were always consistent and actually gave more than average power. The B31 for example always gave at least 17bhp often more. The B33 500cc standard engine was another consistent performer giving 22 - 23bhp when new. The twins were not so good, the A7 500 was better than the A10. The B 31 was a good little engine, a 350cc single, with cast iron head and cylinder. By fitting a few Gold Star parts they were easy to improve. By merely fitting Gold Star cams (touring version) and a Gold Star silencer they would put out 23bhp. By going a little further, fitting eccentric rocker spindles, lighter push rods and tappets, shorter connecting rod, shorten cylinder to suit, Gold Star piston giving 8:1 compression in place of 6.5:1 they would give 27bhp and almost 100mph at no extra cost since these were all production parts. The B33 500 was much the same and could easily give over 30bhp.
Ariel used a BSA A10 in their Huntmaster and one day they complained of lack of power from these engines. I requested them to send me a 'bad' engine and I would test it on our dyno. Sure enough it gave only 27bhp. So we stripped it to see if there were any obvious faults, then gave it another 1 hours running and it was a little better. I noticed that they were using Ariel exhaust pipes and silencers which were different from the A10, larger diameter and slightly shorter and different silencers. We fitted standard BSA pipes and silencers and immediately got 31bhp by fitting one size larger main jet the power was just under 33bhp. We informed Ariel with what we had done but they did not seem keen to change things. Perhaps they liked the appearance of the larger diameter pipes.
The primary aim of my development shop at BSA apart from improving standard machines was to win the Clubmans TT. We were not supposed to be interested in International racing, other than in connection with the MC1 project. The scrambler motor was considered powerful enough. For the Clubmans models we were always searching for a little more speed and of course reliability. This went hand in hand with American class ‘C’ AMA racing, since what was good for the Clubmans was also good for class ‘C’.
BSA did not dominate the early Clubmans 500cc TT races which were won mainly by Triumph and Norton. The 1949 race for 350cc was BSA's first victory. Many BSA 350's were entered and few finished but that year the winner was a BSA.
They had plunger rear suspension, leaked oil, and tended to blow oil out of the engine breather, to the extent of running low on oil, causing seizures etc. Nevertheless, the two or three best BSAs on that occasion did very well, competing against Velocette KSS models and 350 Norton Internationals. In 1952 BSA had hoped to provide a challenge in the 500cc Clubmans with an all alloy twin engine which would be promoted as Gold Star Twin if successful.
However the regulations prevented their use as it was not yet a production model. A few standard A7 500cc twins were built to Clubmans specifications, they pushed out 36-38bhp which was about the same as the production Manx Norton, but in fact were unreliable and had a peaky performance, also did not handle as well as the single. In 1953 it was the same story, the old CB350 did quite well as did the 500cc singles of which there were two or three entered.
The 500cc BSA twins were getting pretty unpopular by that time because when the crankshaft broke, they often destroyed the crankcases and fetched the rider off. If this happens at 100mph it’s pretty scary. Triumphs were still going strong with their 500cc twins although they had their share of blown engines too. They won by the use of specially prepared hand picked machines and some good riders. By 1954 the Gold Star had new heads with big area finning, eccentric rocker spindles, shorter connecting rods, tubular push rods (instead of solid alloy) and Nimonic exhaust valves, a timed crankcase breather (which controlled the tendency to blow oil out on to the road and rear tires) and needle roller bearings on the gearbox layshaft. So far as factory involvement in preparing machines for the Clubmans went there was none, however we used to maintain a workshop in the Island for the benefit of all riders of BSAs. The riders who showed the best in practice might get the benefit of someone like Cyril Halliburn working on their motors. Triumph and Norton did the same thing.
Triumph had Ernie Nott an ex- TT winner working on some of their customers’ bikes. I was in the Island workshop keeping an eye on technical problems and helping Charlie Salt with his TT machines. Before coming to BSA Hopwood had designed the Norton twin, its outstanding feature was the way the cylinder heads were splayed, cut at the front giving better cooling and more fins where needed. This feature was patented, so of course could not be used by BSA.
Nevertheless the new A7 he designed for 1952 was a good rugged engine compared with the earlier BSA twins. It had a weak point in the timing side main bearing and rather small tappets, they wore more rapidly than they should, and also a tendency to vibrate and break crankshafts. We carried out a lot of tests to improve the timing side main bearing trying an all white metal bearing, a copper-lead bearing and a needle roller bearing. This last was far and away the best but required a different oil feed to the crankshaft to lubricate the rod bearings but as the factory did not want to make a change, we continued with the short life main bearing. The crankshaft breakage problem was really due to two things, the diameter of the crankshaft rod bearing journals gave a natural frequency of vibration that coincided with 6,600 & 3,300 RPM, any prolonged full throttle running at 6,600 rpm soon broke the crank adjacent to the rod bearing journal.
A member in the Group Research dept. gave this matter some thought and came up with the answer - a better finish in the fillet radius each side of the big end journal. In production the journal radius was done by the same grinding wheel that ground the journal, this meant that tiny microscopic scratches were left and this is where the fatigue fractures invariably started. His solution was to roll under high pressure a ball around each journal, leaving a perfectly smooth finish.
The layout of the Test shop.There were five Heenan &Froude hydraulic dynamometers and one electric dyno, an elaborate set up ideal for research work. The electric dyno could be reversed to drive the engine you were testing. Everyone was half scared of it, except Arthur Bridgewood, he used it a lot. He insisted that there was always an apprentice standing with his hand on the big knife switch to cut it off dead, if an engine blew up whilst running, current would continue to flow rotating the already damaged engine to destruction. The operator had to be wide awake and act quickly if something broke or seized. We eventually traded this dyno to Research for a nearly new DPX1. The other dynos were two DPX2, one DPX0 and two DPX1. When the MC1 came into the shop we had a new high speed dyno- a DPX3 .
Originally all the dynos were driven by chain from the engine sprocket, a very inefficient method, but simple. We used a 2:1 ratio to keep things simple. Anyone who favours primary chain drive should attend a test using chain drive. At about 6000 RPM take a reading, then get a squirt oil can and oil the chain, the engine will pick up an apparent 2bhp.
Heenan used to recommend a shaft and two universal joints like in a car, but we found them unreliable, the universal joints used to break up and fly all over the shop like shrapnel. We eventually went to a bonded rubber coupling which if lined up carefully gave good results. All the dynamometers were arranged in a line with their axis parallel, very neat, but very impractical, as the blast of cooling air and exhaust blew from one to the next, making it impractical to use more than one engine at a time, due to blast of air and if testing a race engine the noise and fumes, to say nothing of oil.
To try to get away from these difficulties and to control the blowing oil we had some metal shields on castors made which could be rolled around behind the engines. When cooling air blowers were turned on the shields tended to move around, they soon got coated in oil and one had to avoid brushing against the oily surface. This system remained in used for some years until the shop was demolished. The development shop was once a stable, it was quite old, with over 30 foot ceiling and heated by steam pipes. In summer the only cooling was by opening ventilators.
Originally there was no provision for letting air and fumes out, so a rather expensive sheet metal ducting system was built with a 6 hp fan drawing air from just behind each engine. Cooling air was blown over each engine by a powerful 'squirrel cage' blower, giving an 80mph blast. This cooling air was ducted in from the roof and it was possible to select cold outside air or warm inside shop air by operating a flap valve in a ??? WY' joint by means of a cord. When you run an engine under full power on a dyno you have to be wide-awake, if it starts to tighten up or the exhaust note changes you shut it off immediately. If there are two engines running, it is difficult to tell which is about to falter.
There was no objection to running an engine on the shop exhaust system for 'running in' purposes, this running in was an important part of testing a new engine, it will not deliver its best power until it is 'broken in'. Once a month we would take an engine at random from the production line and after a couple of hours of gentle running, take a full power curve, if it was down for power we would strip it to find out why. Should it be badly down on power we would take another engine from the same batch and test it, if it also was bad, we had to get that particular assembly line stopped until the fault could be located and corrected. Needless to say this was an unpopular action, but was necessary to preserve (the factory's reputation.
The only time I can remember actually calling for a halt to production was on the A10 line and later on the C12. Usually what happened was a cumulative effect due to tightness, maybe a worn tool, making one part slightly oversize and a corresponding part slightly undersize. Sometimes an extra hour running on the dyno would be enough to restore the power.
All Gold Stars and Road Rockets were tested by the engine test dept after a period of running in. The cylinder heads and cylinders were removed for inspection and individual power curves issued with each engine. Some BSA production engines were always consistent and actually gave more than average power. The B31 for example always gave at least 17bhp often more. The B33 500cc standard engine was another consistent performer giving 22 - 23bhp when new. The twins were not so good, the A7 500 was better than the A10. The B 31 was a good little engine, a 350cc single, with cast iron head and cylinder. By fitting a few Gold Star parts they were easy to improve. By merely fitting Gold Star cams (touring version) and a Gold Star silencer they would put out 23bhp. By going a little further, fitting eccentric rocker spindles, lighter push rods and tappets, shorter connecting rod, shorten cylinder to suit, Gold Star piston giving 8:1 compression in place of 6.5:1 they would give 27bhp and almost 100mph at no extra cost since these were all production parts. The B33 500 was much the same and could easily give over 30bhp.
Ariel used a BSA A10 in their Huntmaster and one day they complained of lack of power from these engines. I requested them to send me a 'bad' engine and I would test it on our dyno. Sure enough it gave only 27bhp. So we stripped it to see if there were any obvious faults, then gave it another 1 hours running and it was a little better. I noticed that they were using Ariel exhaust pipes and silencers which were different from the A10, larger diameter and slightly shorter and different silencers. We fitted standard BSA pipes and silencers and immediately got 31bhp by fitting one size larger main jet the power was just under 33bhp. We informed Ariel with what we had done but they did not seem keen to change things. Perhaps they liked the appearance of the larger diameter pipes.
Thursday 8 January 2009
Roland Pike Autobiogaphy Chapter 17
HOW THE MC1 BSA'S RACER BROUGHT ME TO THE FACTORY
The story of how I came to work for BSA really started in 1951 when I rode a 1949 Gold Star in the Senior TT and actually finished on it. Through Hallets, my local dealer in Canterbury and Charlie Salt, who already worked in the drawing office of BSA who put me in touch with Herbert Hopwood. I told Mr Hopwood I would like to build two racers for the coming year, using BSA Gold Star engines but in lighter welded frames of my own design. He agreed to supply the engines through my local dealer. After a while I was sent for and told the policy of the company was not to make a 500 Gold Star, but they were willing to provide a 500 twin. I was doubtful, as I did not know anything about twins.
I enquired as to what they would supply me with and they agreed to an all aluminium engine that gave 44 horse power. This sounded terrific to me and I agreed to accepting it. Little did I know how awful the engine was. The power band was so narrow that you could step off it either way in 600 RPM or so. The 44 horsepower was a dynamometer reading that seemed difficult to reproduce on the track. I wasn’t the first to fall for horsepower figures, and I made the two machines one with the unit construction twin and one with a separate Albion gearbox and 350 Gold Star single cylinder engine. I had in the back of my mind to substitute a 500 Gold Star engine if the twin was no good.
I sold my AJS 7R and spent the winter and spring 1951-52 building these two as Pike BSAs. The rear part of the frame looked something like a featherbed Norton, but I used a single front down tube. One bike had an oval & tapered down tube and the other a round one, which subsequently broke and had to be replaced with a tapered oval section tube. Girling rear shock absorbers were fitted and originally Silentbloc swing arm bushes, but these proved to have too much give and had to be replaced with bronze bushes.
Later on when Dennis Lashmar owned the twin, he had many engine blow-ups, so we got permission to put in the 500 Gold Star single. This was two years later when the Gold Star produced 44bhp, and he did very well, engaging in some neck and neck rides with the great John Surtees at Brands Hatch. Surtees told me himself that Dennis used to give him a run for his money. In those days Surtees was running double overhead cam featherbed Nortons, the very best, so Charlie Salt wrote to me and asked "are you going to spend your life building and riding these back yard specials or are you to finally retire and look for a job in the industry?"
If I wrote to Mr. Hopwood at BSA and tell him a little bird told you, but don't mention his name, that you understood there was an opening that would interest me. I don't know why they were so secretive but that was typical of BSA. I wrote to Mr Hopwood and he asked me to come and see him. Hoppy took me to lunch and we had a long chat, about the development shop he'd set up, and the test shop, also the metal shop. The experimental shop built and tested bikes, the test shop did the routine production testing of Gold Star engines. Mr Hopwood had told the bosses they needed a test shop, remember this was in 1951, BSA was the biggest motor cycle manufacturer in the world, and they agreed telling him he could have the shed down by the foundry where Arthur Lupton had been developing an engine. Ever heard of that one? Phillips then patented a "hot air" engine and tried to sell the idea, ??? had carried out a lot of development work on it, and another two years, but they did not make any progress, so was dropped.
A competition rider, Jack Amott was taken out of the test shop and put in charge of development. I never met him, but I think ??? us in many ways. He really started the Gold Star off; and was brilliant at mathematics, but being outspoken he upset Hoppy every other day. Amott had been an old factory Rudge Racer years before and was injured in a crash, at I think Greeba. After that he became a good trials rider to the core. Unfortunately he got himself disliked and Mr Hopwood fired him because of his criticism of the MC1 250 racer then being built at BSA. Unaware of the fact at the time, I was brought in to build the 250 racer. At that time the MC1 wasn’t even in the test shop but in the research dept under Donald Bastow, who want ??? it but was asked to look after it, because of Jack ???.
Bill Bentley was put in the shop to assemble and run it. Every time the engine was run on the dyno, lubrication was ??? and rockers became blue with heat. Jack Amott had told them that the lubrication system was inadequate, they thought he was being obstructive, so he was fired, which paved the way for me to come up from the south to Birmingham to do the job.
I was quite excited about the bike, and asked if they had had it running yet. Not yet was the answer but it will be run any time now and we want you to be here to watch it. I was asked if I had any criticism of the plans, but not wanting to upset anybody I pointed out I was an amateur racer after all, not a professional designer. They insisted however saying I had enough experience and that they valued my opinions. After examining the drawings, I pointed out that I did not think the oil would return to the crankcase from the rocker box due to the almost horizontal angle of the cylinder. Also that I thought plain bushes for the vertical shaft would not take 10,000 - 12,000 rpm. I didn’t think the fine tooth gears for the cam drive would stand up and I did not like the idea of the oil pump case being made of aluminium, and suggested cast iron, which eventually had to be done.
They listened politely to all this criticism from me, perhaps because I was new and had just started to work there, yet they had just fired Jack Amott for saying the same things. Of course they didn’t change anything until it eventually gave trouble, and eventually all the things I had criticised did give trouble, not all at once, but piecemeal, each time causing a delay of a week or months whilst the parts were re-designed and made.
The compression ratio was too high, after burning a number of pistons we went to a forged piston. Bill Bentley insisted on running the engine on 50-50 petrol benzole, as he could not keep it running on the standard pump fuel that TT regulations called for, so he was pulled off the job because of this. Alan Sandilands took over then and by some ingenious modifications to the lubrication system got the cam and rocker wear under control.
The MC1 took up a great deal of time and effort on my part, and the thanks I got for it was hearing via the grapevine that Geoff Duke, who was set to ride the machine had been told it had been taken away from me because I did not believe in it anymore and was said to be holding up progress.
Next they brought in Charlie Edwards the Norton race team mechanic, he was not an engine development expert just a very good and thorough race mechanic, and they seemed to think that as he was a Norton expert he would be able to fix the problems. A small test shop was built and Bill Bentley was assigned back on the MC1 development. Not surprisingly the problems continued, mostly overheating due to insufficient cooling fin area. The primary chain gave problems too, the chain case had as many cooling fins as the cylinder head.
There was a lot of bad feeling and BSA Managing Director Jimmy Leake complained that four years time and money had been wasted and were they going to race it or not? Finally he gave the ultimatum that they could race it if they could win. Finally I was called to a conference and asked if I thought it could win in the Isle of Man and I told them I doubted if you could even finish in the IOM. That was heresy of course, because whatever happened you were supposed to agree.
In the meantime I had got myself into more trouble by building a 250 Gold Star which on test at MIRA timing strip had gone ??? mph faster than the MC1. We had no lightweight frame for this engine and we had used a Gold Star frame. This did not go down very well as Hoppy thought I was trying to make him look foolish and he said "did I think I was smarter than they were?" to which I responded that I was only trying to prove a point, that the Gold Star was fundamentally right and the MC1 was wrong in several ways. I continued to suggest it needed redesigning, more cooling fins and gear primary drive. They had said it wasn’t possible, so my advice was to drop it. That’s how they got the idea that I had it in for the machine, but they were wrong.
I saw a lot of good in the MC1, we had worked hard on that engine, had got it to produce 34bhp at 10,500 albeit unreliably. We could get 31 to 32bhp at 10,000 rpm fairly reliably by dropping compression ratio, but Hoppy would not agree to this, he wanted 10:1 compression ratio. At this time the fuel for racing was about 80 octane.
We had measured the fin area on the cylinder head, it came out at 206 sq. ins. When you realise that the C12 had 224 sq ins, the 350 Gold Star 520 sq. ins and the 350 KTT 600 sq. ins, it was obvious that some difficulty with heat dissipation was likely. The primary chain was not used on the dyno so we had no knowledge of its problems until the engine was installed in the bike. It first showed up as a problem when the gearbox repeatedly moved forwards and tightened the rear chain. An extra strong adjuster had to be made.
Next the chain overheated and rollers flew off. A new chaincase was designed incorporating cooling fins. I believe this phenomena was due to the high rpm causing that chain to experience high centrifugal loading, enough to move the gearbox, there must have been a loss of power due to this, possibly as much 4bhp. Normally the rear chain had the stronger pull due to torque multiplication at the sprockets and gearbox. During the testing of the complete MC1 bike on the test track we had some interesting experiences.
In the Spring of 1954 we reserved use of Silverstone for a day. It was a cold damp day, Charlie Salt clad in racing leathers ready for a days testing, and after warming up the engine Charlie set off, he only covered a quarter of a mile when he returned and complained the bike would not pull, he thought it had seized up. I took a look in the oil tank, revved up the engine but could see no oil returning. So I got astride and letting in the clutch attempted to take off, but realised immediately what was wrong and turned to Hoppy and said "the big end has gone". They all wanted to argue except Hoppy, who accepted my explanation that I had experienced the symptoms before on my 7R. So it was agreed to put the bike back on the trailer. We subsequently discovered that the so-called experts in the experimental department who had installed the engine had reversed the oil pipe lines from tank to engine, so that it got no oil through and crankshaft was ruined. They were all intrigued to know I was so sure of my diagnosis and so quickly as there was no tell tale "knock". I recounted how with my 7R at Scarborough one time when running an alloy connecting rod with plain big end bearing I experienced the same symptoms.
The next testing was at MIRA test track on Good Friday 1954. This time we had a good run round the outer circuit, Charlie Salt lapping at 100-102mph, I was a little slower due to my extra bulk and weight. We then went to the timed straight and ran the bike up and down timing in each direction, Charlie was timed at 104mph in one direction. I took my turn and got over 100mph mark in one direction turned around to get a run back and had got up to the maximum speed and was approaching the timing lights when the bike started to weave and snake about, I shut off and gently eased the bike on the front brake, thinking I had a burst rear tyre.
Finally at about 120mph it went almost out of control and I averted a spill by jamming both feet on the ground. The back wheel had collapsed. They had used cast iron for a spoke flange on one side, this broke up and allowed all the spokes on one side to come loose, I had to push the bike back to where they were all waiting.
It was a comfortable, good steering bike and quite light. The Earles forks were specially made by BSA for this machine. A novel feature was the head stem arrangement, this being reversed from the usual set up. On the MC1 the head stem was fixed at Back to top and bottom to the frame and the head lug rotated about it, this allowed lower front end and fitted in with streamlined fuel tank, funnily enough I had suggested this arrangement to Doug Hele, when we were discussing a fork crown to clear the tank. The original fuel tank fitted at this time held less fuel than the later one which was intended to do the Lightweight TT non-stop.
We had the whole machine in a wind tunnel at Cranfield RAF College, to get the wind resistance down, the results led to a more streamlined tank. The people concerned with BSA racing (Hopwood, Doug Hele, Dennis Hardwick and Charlie Salt) all seemed quite happy with the performance of the 250cc racer but the 1954 TT came and went and the 250cc NSU was said to develop 38bhp and judging by the way they flew past everyone else this was no exaggeration. As it turned it out it was a good job we did not enter for the IOM with the MC1. I had some ideas for further development but was not allowed to do much more than change jets, we should have experimented with inlet pipe lengths, exhaust pipe length and diameter, even maybe some different cams, but unfortunately we spent two years just keeping it running.
When I was first at BSA I lived in lodgings near the factory, riding home to Canterbury each weekend - 186 miles each way. The experimental dept. loaned me a bike for this purpose. Most of the time I had a 1952 Gold Star touring version with lights & silencer and mag dyno. This machine had telescopic front forks and plunger rear suspension, with a hydraulic damper built in. It worked quite well, the performance with low compression and standard sports cams was quite moderate, maximum speed about 82-85mph. This commuting went on until late August 1952 when I bought a house in Olton.
I purchased a 1952 Gold Flash sidecar outfit from the company, the whole thing was overhauled and repainted dark red. I kept this outfit for some time and did quite a big mileage on it, experiencing most of the problems that customers had such as primary chain case running dry at steady 50mph crumbling, timing side main bearing failure and a broken sidecar connection, said incident occurring 80 miles from home at the start of our vacation on a Saturday, was fortunate to find a garage that allowed me to make sufficient repairs using their tools so that we could return home - the family’s comments will not be recorded.
Next post - Roland Pike Autobiography Chapter 18 - The Development Shop & Clubmans TT
The story of how I came to work for BSA really started in 1951 when I rode a 1949 Gold Star in the Senior TT and actually finished on it. Through Hallets, my local dealer in Canterbury and Charlie Salt, who already worked in the drawing office of BSA who put me in touch with Herbert Hopwood. I told Mr Hopwood I would like to build two racers for the coming year, using BSA Gold Star engines but in lighter welded frames of my own design. He agreed to supply the engines through my local dealer. After a while I was sent for and told the policy of the company was not to make a 500 Gold Star, but they were willing to provide a 500 twin. I was doubtful, as I did not know anything about twins.
I enquired as to what they would supply me with and they agreed to an all aluminium engine that gave 44 horse power. This sounded terrific to me and I agreed to accepting it. Little did I know how awful the engine was. The power band was so narrow that you could step off it either way in 600 RPM or so. The 44 horsepower was a dynamometer reading that seemed difficult to reproduce on the track. I wasn’t the first to fall for horsepower figures, and I made the two machines one with the unit construction twin and one with a separate Albion gearbox and 350 Gold Star single cylinder engine. I had in the back of my mind to substitute a 500 Gold Star engine if the twin was no good.
The frame that Roland built - all welded & lighter than the BSA frame
I sold my AJS 7R and spent the winter and spring 1951-52 building these two as Pike BSAs. The rear part of the frame looked something like a featherbed Norton, but I used a single front down tube. One bike had an oval & tapered down tube and the other a round one, which subsequently broke and had to be replaced with a tapered oval section tube. Girling rear shock absorbers were fitted and originally Silentbloc swing arm bushes, but these proved to have too much give and had to be replaced with bronze bushes.
Later on when Dennis Lashmar owned the twin, he had many engine blow-ups, so we got permission to put in the 500 Gold Star single. This was two years later when the Gold Star produced 44bhp, and he did very well, engaging in some neck and neck rides with the great John Surtees at Brands Hatch. Surtees told me himself that Dennis used to give him a run for his money. In those days Surtees was running double overhead cam featherbed Nortons, the very best, so Charlie Salt wrote to me and asked "are you going to spend your life building and riding these back yard specials or are you to finally retire and look for a job in the industry?"
If I wrote to Mr. Hopwood at BSA and tell him a little bird told you, but don't mention his name, that you understood there was an opening that would interest me. I don't know why they were so secretive but that was typical of BSA. I wrote to Mr Hopwood and he asked me to come and see him. Hoppy took me to lunch and we had a long chat, about the development shop he'd set up, and the test shop, also the metal shop. The experimental shop built and tested bikes, the test shop did the routine production testing of Gold Star engines. Mr Hopwood had told the bosses they needed a test shop, remember this was in 1951, BSA was the biggest motor cycle manufacturer in the world, and they agreed telling him he could have the shed down by the foundry where Arthur Lupton had been developing an engine. Ever heard of that one? Phillips then patented a "hot air" engine and tried to sell the idea, ??? had carried out a lot of development work on it, and another two years, but they did not make any progress, so was dropped.
A competition rider, Jack Amott was taken out of the test shop and put in charge of development. I never met him, but I think ??? us in many ways. He really started the Gold Star off; and was brilliant at mathematics, but being outspoken he upset Hoppy every other day. Amott had been an old factory Rudge Racer years before and was injured in a crash, at I think Greeba. After that he became a good trials rider to the core. Unfortunately he got himself disliked and Mr Hopwood fired him because of his criticism of the MC1 250 racer then being built at BSA. Unaware of the fact at the time, I was brought in to build the 250 racer. At that time the MC1 wasn’t even in the test shop but in the research dept under Donald Bastow, who want ??? it but was asked to look after it, because of Jack ???.
Bill Bentley was put in the shop to assemble and run it. Every time the engine was run on the dyno, lubrication was ??? and rockers became blue with heat. Jack Amott had told them that the lubrication system was inadequate, they thought he was being obstructive, so he was fired, which paved the way for me to come up from the south to Birmingham to do the job.
I was quite excited about the bike, and asked if they had had it running yet. Not yet was the answer but it will be run any time now and we want you to be here to watch it. I was asked if I had any criticism of the plans, but not wanting to upset anybody I pointed out I was an amateur racer after all, not a professional designer. They insisted however saying I had enough experience and that they valued my opinions. After examining the drawings, I pointed out that I did not think the oil would return to the crankcase from the rocker box due to the almost horizontal angle of the cylinder. Also that I thought plain bushes for the vertical shaft would not take 10,000 - 12,000 rpm. I didn’t think the fine tooth gears for the cam drive would stand up and I did not like the idea of the oil pump case being made of aluminium, and suggested cast iron, which eventually had to be done.
They listened politely to all this criticism from me, perhaps because I was new and had just started to work there, yet they had just fired Jack Amott for saying the same things. Of course they didn’t change anything until it eventually gave trouble, and eventually all the things I had criticised did give trouble, not all at once, but piecemeal, each time causing a delay of a week or months whilst the parts were re-designed and made.
The compression ratio was too high, after burning a number of pistons we went to a forged piston. Bill Bentley insisted on running the engine on 50-50 petrol benzole, as he could not keep it running on the standard pump fuel that TT regulations called for, so he was pulled off the job because of this. Alan Sandilands took over then and by some ingenious modifications to the lubrication system got the cam and rocker wear under control.
The MC1 took up a great deal of time and effort on my part, and the thanks I got for it was hearing via the grapevine that Geoff Duke, who was set to ride the machine had been told it had been taken away from me because I did not believe in it anymore and was said to be holding up progress.
Next they brought in Charlie Edwards the Norton race team mechanic, he was not an engine development expert just a very good and thorough race mechanic, and they seemed to think that as he was a Norton expert he would be able to fix the problems. A small test shop was built and Bill Bentley was assigned back on the MC1 development. Not surprisingly the problems continued, mostly overheating due to insufficient cooling fin area. The primary chain gave problems too, the chain case had as many cooling fins as the cylinder head.
There was a lot of bad feeling and BSA Managing Director Jimmy Leake complained that four years time and money had been wasted and were they going to race it or not? Finally he gave the ultimatum that they could race it if they could win. Finally I was called to a conference and asked if I thought it could win in the Isle of Man and I told them I doubted if you could even finish in the IOM. That was heresy of course, because whatever happened you were supposed to agree.
In the meantime I had got myself into more trouble by building a 250 Gold Star which on test at MIRA timing strip had gone ??? mph faster than the MC1. We had no lightweight frame for this engine and we had used a Gold Star frame. This did not go down very well as Hoppy thought I was trying to make him look foolish and he said "did I think I was smarter than they were?" to which I responded that I was only trying to prove a point, that the Gold Star was fundamentally right and the MC1 was wrong in several ways. I continued to suggest it needed redesigning, more cooling fins and gear primary drive. They had said it wasn’t possible, so my advice was to drop it. That’s how they got the idea that I had it in for the machine, but they were wrong.
I saw a lot of good in the MC1, we had worked hard on that engine, had got it to produce 34bhp at 10,500 albeit unreliably. We could get 31 to 32bhp at 10,000 rpm fairly reliably by dropping compression ratio, but Hoppy would not agree to this, he wanted 10:1 compression ratio. At this time the fuel for racing was about 80 octane.
We had measured the fin area on the cylinder head, it came out at 206 sq. ins. When you realise that the C12 had 224 sq ins, the 350 Gold Star 520 sq. ins and the 350 KTT 600 sq. ins, it was obvious that some difficulty with heat dissipation was likely. The primary chain was not used on the dyno so we had no knowledge of its problems until the engine was installed in the bike. It first showed up as a problem when the gearbox repeatedly moved forwards and tightened the rear chain. An extra strong adjuster had to be made.
Next the chain overheated and rollers flew off. A new chaincase was designed incorporating cooling fins. I believe this phenomena was due to the high rpm causing that chain to experience high centrifugal loading, enough to move the gearbox, there must have been a loss of power due to this, possibly as much 4bhp. Normally the rear chain had the stronger pull due to torque multiplication at the sprockets and gearbox. During the testing of the complete MC1 bike on the test track we had some interesting experiences.
In the Spring of 1954 we reserved use of Silverstone for a day. It was a cold damp day, Charlie Salt clad in racing leathers ready for a days testing, and after warming up the engine Charlie set off, he only covered a quarter of a mile when he returned and complained the bike would not pull, he thought it had seized up. I took a look in the oil tank, revved up the engine but could see no oil returning. So I got astride and letting in the clutch attempted to take off, but realised immediately what was wrong and turned to Hoppy and said "the big end has gone". They all wanted to argue except Hoppy, who accepted my explanation that I had experienced the symptoms before on my 7R. So it was agreed to put the bike back on the trailer. We subsequently discovered that the so-called experts in the experimental department who had installed the engine had reversed the oil pipe lines from tank to engine, so that it got no oil through and crankshaft was ruined. They were all intrigued to know I was so sure of my diagnosis and so quickly as there was no tell tale "knock". I recounted how with my 7R at Scarborough one time when running an alloy connecting rod with plain big end bearing I experienced the same symptoms.
The next testing was at MIRA test track on Good Friday 1954. This time we had a good run round the outer circuit, Charlie Salt lapping at 100-102mph, I was a little slower due to my extra bulk and weight. We then went to the timed straight and ran the bike up and down timing in each direction, Charlie was timed at 104mph in one direction. I took my turn and got over 100mph mark in one direction turned around to get a run back and had got up to the maximum speed and was approaching the timing lights when the bike started to weave and snake about, I shut off and gently eased the bike on the front brake, thinking I had a burst rear tyre.
Finally at about 120mph it went almost out of control and I averted a spill by jamming both feet on the ground. The back wheel had collapsed. They had used cast iron for a spoke flange on one side, this broke up and allowed all the spokes on one side to come loose, I had to push the bike back to where they were all waiting.
It was a comfortable, good steering bike and quite light. The Earles forks were specially made by BSA for this machine. A novel feature was the head stem arrangement, this being reversed from the usual set up. On the MC1 the head stem was fixed at Back to top and bottom to the frame and the head lug rotated about it, this allowed lower front end and fitted in with streamlined fuel tank, funnily enough I had suggested this arrangement to Doug Hele, when we were discussing a fork crown to clear the tank. The original fuel tank fitted at this time held less fuel than the later one which was intended to do the Lightweight TT non-stop.
We had the whole machine in a wind tunnel at Cranfield RAF College, to get the wind resistance down, the results led to a more streamlined tank. The people concerned with BSA racing (Hopwood, Doug Hele, Dennis Hardwick and Charlie Salt) all seemed quite happy with the performance of the 250cc racer but the 1954 TT came and went and the 250cc NSU was said to develop 38bhp and judging by the way they flew past everyone else this was no exaggeration. As it turned it out it was a good job we did not enter for the IOM with the MC1. I had some ideas for further development but was not allowed to do much more than change jets, we should have experimented with inlet pipe lengths, exhaust pipe length and diameter, even maybe some different cams, but unfortunately we spent two years just keeping it running.
When I was first at BSA I lived in lodgings near the factory, riding home to Canterbury each weekend - 186 miles each way. The experimental dept. loaned me a bike for this purpose. Most of the time I had a 1952 Gold Star touring version with lights & silencer and mag dyno. This machine had telescopic front forks and plunger rear suspension, with a hydraulic damper built in. It worked quite well, the performance with low compression and standard sports cams was quite moderate, maximum speed about 82-85mph. This commuting went on until late August 1952 when I bought a house in Olton.
I purchased a 1952 Gold Flash sidecar outfit from the company, the whole thing was overhauled and repainted dark red. I kept this outfit for some time and did quite a big mileage on it, experiencing most of the problems that customers had such as primary chain case running dry at steady 50mph crumbling, timing side main bearing failure and a broken sidecar connection, said incident occurring 80 miles from home at the start of our vacation on a Saturday, was fortunate to find a garage that allowed me to make sufficient repairs using their tools so that we could return home - the family’s comments will not be recorded.
Next post - Roland Pike Autobiography Chapter 18 - The Development Shop & Clubmans TT
The Roland Pike story
For my very first post in my very first blog I decided to write about a BSA person rather than a BSA motorcycle.That person is Roland Pike and there are a number of reasons for choosing him. First and foremost, he is someone that had interested me for a long time before I ever started my first BSA websites. Second, is that I've detected an increasing background count of interest in printed features, online postings and other websites over the last year or so. But the tipping point was an email from an aquaintance who has a longer standing and more personal interest in Roland Pike than I do. He emailed me to ask how I was doing and to point out a couple of errors in some material I had posted about Roland on my old BSA website. That was the tipping point - Roland was first up.
So in this post I'll introduce Roland Pike but in subsequent posts I will his unpublished biography of his time working with BSA.
Roland Pike was a development engineer at BSA between 1952 and 1957. After that he left to work with SU Carburetters for a while then emigrated with his family to the USA in 1959.
Taking a job temporarily as a sports car dealership mechanic in Roanoke, Virginia and after settling in, he went to work as a field tech rep for Jaguar in New York, and finally on to Volkswagen Atlantic, a several-state distributorship, where he did the same job and held schools for mechanics. He stayed there to retirement, then moved to Inman, South Carolina where for more years he had a backyard shop rebuilding VW transaxles. This was in the air-cooled VW era when US roads were still covered with millions of them. Roland was always fond of the air-cooled model.
Some years ago while researching BSA's Daytona Racers I tried to find Roland Pike as I had many questions to ask him about his work on these bikes and at BSA in general. I knew he had been living in the US for some time but I didn't have a contact address.
I eventually managed to get in touch with his daughter but unfortunately a week or two after he died. However, his daughter very kindly gave me a paper copy of his BSA memoirs with permission to publish these on a website as long as they were used for research and enthusiast purposes only.
So in the following posts are the memoirs, scanned, OCR'ed and mostly proofed (I'm still spotting some of my own typos) from the original handwritten notes. They are presented in the original form with chapters that start at 17 (I think the previous published volume had chapters 1 - 16) and with chapter 25 missing.
The memoirs are a gold mine of information for BSA enthusiasts or anyone interested in the internal workings of the British motorcycle industry during the early to late 1950's. As a snapshot of the politics and machinations they provide an interesting counterpoint to that presented in Bert Hopwood's book 'Whatever Happened to the British Motorcycle Industry'. As a piece of technical the memoirs provides a view at odds with some of the accepted wisdom about BSA motorcycles such as the MC1. They are also unashamedly opinionated, most notably in favour of the Gold Star.
But they show Roland to be someone who was too professional to let his preferences influence the effort or ingenuity he would commit, even to bikes he privately thought were developmental dead-ends.
For a few years in the early 1950's BSA arguably had the very best design and development team that ever worked in the British motorcycle industry. Bert Hopwood, Doug Hele... and Roland Pike.
Thanks to Bill Hoddinott for details about Roland's life during and -post BSA.
Thanks to Carol Smoogen for providing a copy of the Roland Pike unpublished autobiogaphy.
Next post - Roland Pike Autobiography Chapter 17. How the MC1 Racer brought me to the factory
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