The Yamaha RD400 marked a high point in development of the two stroke motorcycle. Not the biggest and most powerful, but the most balanced and well designed. The RD400 had a six speed transmission and front and rear disk brakes years before they were common. Trials like stability was coupled with a high power to weight ratio, at an affordable price. In the mid to late 70s, RD400s were the boy racer's weapon of choice.