By the early 1980s, two-stroke engines were under threat across Europe. Governments were moving toward bans. Yamaha responded with one valve. The YPVS — Yamaha Power Valve System. A motorised exhaust valve that made the two-stroke manageable at low RPM and explosive above it. One engine. Two completely different characters. Honda, Suzuki, and Kawasaki all built their own versions. Two-stroke road bikes survived for another fifteen years because of it. . . . #OneLungRacing #Yamaha #YPVS #PowerValve #RD350 #TwoStroke #2Stroke #YamahaRD #MotorcycleEngineering #VintageMotorcycles #TwoStrokeLife #MotorcycleHistory #RZ350 #ClassicBikes #EngineeringBreakthrough #MotoHistory #YamahaRacing #TwoStrokePower #RD350YPVS #MotorcycleMechanics