A  History of Classic Racing  50cc Motorcycles



Philip Conrad Vincent (14 March 1908 – 27 March 1979) was a British motorcycle designer and manufacturer. Founder of Vincent Motorcycles, his designs influenced the development of motorcycles around the world.

Philip bought his first motorcycle, a second-hand 350cc BSA from Gamages in Holborn at Christmas 1924 which vibrated badly and was replaced by an ABC; he designed his first bike in 1925. In October 1926 he went up to read Mechanical Sciences at King's College, Cambridge. His father agreed that he could have a break from university to develop his first "Vincent Special", with a 350 cc MAG engine, in 1927.

In 1928 he had registered a patent for his design of cantilever rear suspension and left Cambridge before graduating. The prototype used his own design of diamond-shaped frame constructed from short-tubes having 'lug' ends consistent with technology of the time, combined with his twin-spring, friction-damped cantilever rear suspension. 

Other main components added were proprietary – Webb front forks, Royal Enfield brakes, Moss gearbox and a McEvoy fuel tank.

In 1935 the first Vincent powered motorcycle, the 499 cc Comet model was launched. Production 1935-1955, Engine 499 cc single-cylinder, OHV, air-cooled, Power 28 bhp @ 5,800 rpm

It was quickly followed by the 998 cc Series A "Rapide" in 1936, as when company owner Phil Vincent saw the drawing based on the his earlier model and in-house engine, he was immediately enthusiastic, and a few weeks later the first Vincent 998 had been made using Meteor upper engine parts mounted on newly designed crankcase.

During the 1960s Phil Vincent contributed to motorcycling journals, writing technical articles as a freelancer. One of the journals was Motorcycle Sport. The following is based on an article in this magazine with other references and pictures added.

WHY TALK DOWN 50 c.c. RACING? (P. C. Vincent 1967)

I SEE that it is becoming widely considered that the 50 c.c. racing class has just about “had” it. While I can understand this, looking at it from the point of view that racing is primarily a spectacle to appeal to the spectators, I can’t help feeling somewhat surprised at the manufacturers’ lack of interest in the class.

With the rapidly increasing performance of the little machines, which is closing the gap between the winning speeds of the 500 c.c. and the 50 c.c. classes, it seems aa pity that the class which provides the greatest opportunity to show up the respective merits of engine design should be allowed to flag.  In 1962, the first year that the 50 c.c. T.T. was run, the record T.T. winning race speeds were: 

Senior 103.51 m.p.h., 
Junior 99.59 m.p.h.,
250 c.c. 98.38 m.p.h.,
125 c.c. 89.88 m.p.h.,
50 c.c. 75.12 m.p.h.

All these speeds were set in 1962 except the 250c.c. speed, which was established in 1961. The equivalent records today (1967) are:

Senior 105.62 m.p.h. (2 per cent. increase)
Junior 104.68 m.p.h. (5 per cent. increase)
250 c.c. 103.07 m.p.h.  (5 per cent. increase)
125 c.c. 97.48 m.p.h. (8 per cent. increase)
50 c.c. 82.89 m.p.h. (10 per cent. increase) (with Graham loafing around under instructions).

This year’s “tiddler” winning, speed “not trying,” would have won the Senior T.T. only 20 years ago, in 1947, the Junior as recently as 1948, the 250 c.c. in any year up to and including 1951 and the 125 c.c. very easily in any year to 1959 inclusive. In 1959 the 125c.c. winning speed was only 74.06 m.p.h., nearly 9 m.p.h. down on the “tiddlers” this year yet look at the one-two-fives now with 97.48 m.p.h. this June.  ( P.V.C. thinks Stuart Graham could have averaged 87 m.p.h.)

Greatest growth potential ‘The 50c.c.’ is the great potential-growth class. As the speeds for this year showed, from 250 c.c. to 500 c.c. there were only very small changes in the winning speeds. Even the one-two-fives are beginning to breathe down their necks and will be right up with the bigger classes in another four or five years, by which time all the four largest classes will be providing their riders with just about all the power that can be gainfully employed. For there is no advantage in spinning the rear wheel harder.

The fact that Agostini’s 3.25in-section rear tyre was bald in the middle of the tread at the finish of the Junior, after only six laps, shows that the torque applied to the rear wheel is approaching the limit of wheel grip. The spread of only 2.5m.p.h. between 250 and 500 c.c. winning speeds shows how close to the limit set by the course the power output has now become. 

In coming years, therefore, the 50 c.c. provides engine designers with the best opportunities for showing us what they can do, and for showing us which designs are best for speed and power. Nor need the spectators turn away with groans of disgust, because I can see no reason why the 50s should not increase their speeds until they too are knocking on the door of the “ton” lap.

Nor need that time be so very long delayed if designers do some original thinking and get those motors really buzzing on an efficiently charged two-stroke cycle that provides worthwhile BMEP. 

Brake Mean Effective Pressure (BMEP) ) is another very effective yardstick for comparing the performance of an engine of a given type to another of the same type, and for evaluating the reasonableness of performance claims or requirements. The definition of BMEP is: the average (mean) pressure which, IF imposed on the pistons uniformly from the top to the bottom of each power stroke, would produce the measured (brake) power output. Please note that BMEP is purely theoretical and has NOTHING to do with ACTUAL CYLINDER PRESSURES. (Editor)

A 50 c.c. multi on the two-stroke cycle should be capable of revving at about 30,000 r.p.m., with gas pressures to help in reversing the piston travel at every t.d.c., if only proper lubrication is provided to enable the engines to run at such high speeds. 

Even on the present very low b.m.e.p.s., that would lift its power output to around 30 b.h.p. and its T.T. lap speeds to well over 90 m.p.h., before tackling the question of providing reasonably efficient induction of the charge! So for heaven’s sake let’s keep what promises to be the most instructive class for engine developers; the one class where positive improvements to engine performance can be reflected in noticeable rise in race and lap speeds.  

From the race promoter’s point of view there is another angle of interest of high value for future years. The mass of the public undoubtedly love to see new records established, and the hope of witnessing the best performance ever acts as a powerful magnet to draw the crowds. In the not-too-distant future we may find ourselves with the optimum power for the larger classes, so that new records will have to come from ideal conditions, even higher qualities in the rider, or course improvements.

The first is seldom granted to us, rider skill is already so high that it is hard to see this taking us very much further, and there is no satisfaction in going faster only because the course has been made easier. So the race organizers should think twice before discarding the only class that is promising the continued production of new records for quite a long time ahead.  


THE F.I.M. should give close consideration to some regulation that will prevent a repetition of the farce in this year’s 50 c.c. T.T., when two of the Suzuki riders were forced to dawdle about while the third, who had been selected to be the winner, made up time lost through changing a plug. The sport of motorcycling suffers severely from stupid actions like this, which tend to make a mockery of race results.

Comments from a journalist for the Motor Cycling magazine 1967:

'But the race itself was both boring and farcical. Suzuki had decreed that Yoshimi Katayama should win. So, when their Japanese team-mate lost over two minutes early on the first lap changing an oiled plug, Graham and a Hans-Georg, on the other two Suzukis had to dawdle round until he caught them up! 

 Entering into the spirit of the slow-motion “race,” they went so painfully slowly that Katayama overhauled them in Ramsey on the second lap. But then, when neck and neck with Anscheidt, he looked round at the German’s oil-filmed rear wheel and rode straight into the bank on the Mountain Mile!

 And chances of the three remaining teamsters making a fight of it on their water-cooled, twin-cylinder two strokes, capable of 110 mph, are remote, It's, open secret that Suzuki have decided that Yoshimi Katayama shall be the winner if he can keep going.

With the whole future of the race in the balance, Suzuki’s thinking is difficult to understand. And neither the reigning “tiddler” champ, Hans-Georg Anscheidt nor 125cc hero Stuart Graham, the other Suzuki men, are particularly happy at riding to "orders." Editor.'

By all means a team manager is entitled to select the order of his finishers, provided that they all have clear runs, because it would be foolish to have them scrapping needlessly together and thus blowing up. But when you have a race that already lacks entries, and in which the only factory-entered team possesses a great superiority over all the other competitors, it is an insult to the organizers and to the spectators to fool about in the manner that the Suzuki riders were instructed to do.

Apart from gaining Suzuki a very bad press in race reports, it severely reduced their eventual winning speed, thus doing them more harm than they expected. Stuart Graham would have finished in under 1 hour 20 minutes at an average of over 85 m.p.h. had he not been compelled to waste so much time in the first two laps. 

Had a rival pushed him hard he could have put up an even better speed than this, well on the way towards a 90-m.p.h. average. This is particularly pertinent to my earlier remarks that the 50c.c. class is the growth class, for had Graham been allowed to average even 85 m.p.h. that class would have shown over 13 per cent. increase in its race speeds over the last five years. I believe that, if pushed, he could have averaged 87 m.p.h., or 16 per cent. increase in race speed in the five years since 1962.

In 1948, the Vincent-H.R.D Owner's Club was formed - the first international one-make Club independent of a manufacturer - and in 1999 they held their Golden Jubilee International Rally in the Isle of Man, when a total of 234 Vincent motorcycles from a total of 17 different countries took to the famous circuit - how proud P.C.V would have been, but sadly he passed away in 1979. His ashes are interred in the family plot at St. Paul's Church, Horndon on the Hill.

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