05/31/2026
The 1977–1978 Yamaha RD400 represents the golden height of the air-cooled, two-stroke street machine before emissions laws pushed the industry toward four-stroke engines. Evolving from the legendary RD350, the RD400 series (specifically the RD400D in 1977 and RD400E in 1978) was built as a lightweight, sharp-handling "giant killer" capable of outperforming contemporary four-stroke bikes with twice the displacement.
The RD400 is often regarded as the final and best-developed air-cooled Yamaha two-stroke street motorcycle before stricter emissions regulations led to the decline of large-displacement two-strokes. Today, it remains one of the most collectible Japanese classic motorcycles of the 1970s, especially among enthusiasts of vintage performance machines.
