1966 Woolley Yamaha 50cc Racing Motorcycle
Motorcycle engineer Brian Woolley was one of Britains foremost two-stroke engine specialists and is perhaps best remembered for helping to develop the Greeves Silverstone production racer. The unique machine offered here was created by Brian in collaboration with Bob Stevenson and first raced in 1966 by Trevor Burton. It is powered by a 1964 Yamaha YS-1 roadster engine modified by the addition of a water-cooling jacket in the interests of reliability. Tuning work consisted of the usual port job, fitting an 18mm DellOrto carburettor and replacing the rotary inlet valves compressed paper disc with a Tufnol part giving longer opening. Small capacity engines with relatively narrow power bands are best served by multi-speed gearboxes (Suzukis 50cc RK67 twin used 14 speeds!) and Woolley ingeniously doubled up the Yamahas four ratios by using an auxiliary transmission in the form of an American-built Gomatic high/low unit, carried on the swinging arms left leg. Motor Cycling explained the change procedure when its tester Bruce Main-Smith rode the Woolley Yamaha at the end of the 1966 season: In reality, the rider starts in low and bottom, changes three times on the gearbox to reach top, then shifts into high. Total five. It is not practical to run through all eight ratios on the trot but the Gomatics half a ratio is useful on hills to get exactly the right cog. The modified YS-1 engine was installed in a purpose-built spine-type frame equipped with Suzuki front fork, Bianchi front brake and Itom rear hub. BMS found that the bike steered impeccably and held the road like glue. The brakes were entirely adequate and the gearchange light and neat.
Completed in the summer of 1966, the Woolley Yamaha with Trevor Burgess aboard had won twice at Cadwell Park, once at Darley Moor and finished second in the Temple 100 in Ireland by the seasons end. Motor Cycling estimated the Yamahas top speed to be the same as that of Hondas CR110 over-the-counter 50cc racer not bad for a home-built special. Kept on museum display for the last 15 years, this unique racing 50 is in running condition but will require re-commissioning before returning to the racetrack. The machine is offered with a copy of Motor Cyclings article and a quantity of spares.
- Please note, the registration 'BH 9852' (printed in the catalogue) does not relate to this machine. We cannot locate the frame or engine number.