50cc.

This elegant CR50 Tohatsu Runpet production roadracer had a sand-cast engine and 4-speed gearbox. 6.8 BHP at 12,000 RPM. A genuine factory production GP bike of 50cc, twin cylinder, 6-speed, with tiny remote float Del'Orto look-alike carbs and magesium brakes, producing 11+ BHP at 13,000 RPM. Via: Marc Lewis