From Yamaha Wiki
The Yamaha RD56 was a Two stroke 250cc Grand Prix motorcycle racing racing motorcycle. It had two 56x50mm cylinders, disk valves and an Oldham coupler joining the crank shafts. Power was 47bhp at 11,000rpm. Although the engine was essentially the same as that of the RD48, the frame was a new design based on the Norton Motorcycle Company. It featured a 7 speed gearbox.
It was ridden by Jim Redman, Yoshikazu Sunako, Fumio Ito, Hiroshi Hasegawa and Tony Godfrey for the 1963 Grand Prix motorcycle racing season.
The engine was improved for the 1964 Grand Prix motorcycle racing season generating a claimed 50bhp at 11,000 rpm. Phil Read joined the Yamaha team replacing Redman who he narrowly beat to become Grand Prix World Champion.
|Manufacturer||Yamaha Motor Company|
|Production||1963 - 1964|
|Engine||250Cubic centimeter Two-stroke cycle|
MacKellar, Colin (28 Aug 1995). Yamaha: All Factory and Production Road-Racing Two-Strokes from 1955 to 1993. UK: The Crowood Press Ltd. pp. 191. ISBN 1852239204.