BMW WR 750

The BMW WR 750 was a supercharged racing motorcycle that BMW first built in 1929 and developed through 1935 solely for racing by the factory. It used a longitudinally mounted two-cylinder, four-stroke flat twin engine with overhead valves and a compressor mounted on top of the gearbox, with boost pressure of up to 2 bar, and the WR 500 and WR 750 works racebikes were derived from the R 37. The idea of supercharging the flat twin came from the designer Rudolf Schleicher, and the concept passed to the racing mechanic Josef Hopf and the works rider Ernst Jakob Henne. On 19 September 1929 Henne set BMW's first official world speed record on a WR 750, 216.75 km/h over the mile with a flying start, and the machine took the motorcycle land-speed record on five occasions, the last in 1935 at 159.10 mph, before the Type 255 took over from 1936.