In 1972, the AMA announced that the displacement limit for racing motorcycles would be 750cc for all engine types. Suzuki and Kawasaki already had three-cylinder two-stroke production-based bikes ready to be modified into 750 racers. Yamaha did not. Despite this, they campaigned their latest 350cc two-stroke twin, and still managed to win the Daytona 200 in 1972 and 1973 after the poor-handling, 100-horsepower 750 two-stroke Triples had exceeded the capabilities of their chassis and tires.
Yamaha had originally planned to offer a production 750 cc two-stroke four cylinder - the GL750, but the EPA crack-down on emissions had begun, and Yamaha knew such a bike would have a short lifespan in the showrooms. Yamaha had other surprises ready. One was a 500cc Grand Prix bike, the 0W20, based on the GL750 architecture. This was conceptually two of Yamaha’s racing 250cc Twins set side-by-side, each with a thin gear on the inner end of its crank and that pair of gears meshing with a double-width gear on a jackshaft extending to drive a dry clutch on the right.
The other surprise was to hire Giacomo Agostini away from MV Agusta - the team he had ridden for since 1966. And meanwhile they prepared a larger, four-cylinder, 695 cc reed-valve two-stroke engine - coded 0W19Read More