| BMW Type 255 Kompressor | |
| Aka: | Type 255 RS 500 |
| Manufacturer: | BMW Motorrad |
| Production: | 1935–1939 |
| Predecessor: | BMW WR 750 |
| Class: | Street racing |
| Engine: | 492 cc DOHC supercharged boxer twin with aluminium cylinders; magnesium engine block and supercharger casing Fuel: gasoline-oil mix |
| Bore Stroke: | 66×72 mm |
| Top Speed: | c. 220km/h |
| Power: | 60hp |
| Transmission: | 4-speed, shaft drive |
| Frame: | Tubular steel twin cradle |
| Suspension: | Front: Oil-filled telescopic forks Rear: Rigid (1935–1936) Plunger (after 1936) |
| Wet Weight: | 138kg (304lb) |
BMW Type 255 Kompressor (also known as the 500 Kompressor, RS 255, RS255 and Type 255 RS 500) was a supercharged boxer twin race motorcycle from the 1930s. A BMW 255 Kompressor was ridden to victory by Georg Meier in the 1939 Isle of Man TT and the first win by a non-British competitor in the premier 500cc Senior TT class.[1] A similar BMW 255 Kompressor machine was auctioned in 2013 for US$480,000, the second-highest price ever paid at auction for a motorcycle.
A Zoller sliding vane supercharger is bolted to the front of the DOHC engine, driven directly by the crankshaft, and is lubricated by castor oil added to the fuel. It provided c. 15psi.
The machine set a number of race records, including the first lap over at a major event, when Georg Meier won the Belgian motorcycle Grand Prix in 1939, and Ernst Jakob Henne's capture of the motorcycle land-speed record in 1936 on a model with a streamlined fairing.
An example is on display at the BMW Museum in Munich.