WTF does that mean?
YPVS
WHAT DOES IT MEAN?
Yamaha Power Valve System
WHAT IS IT?
The original variable port timing mechanism that revolutionised two-stroke performance. First used on Yamaha’s motocross and GP bikes back in the 1970s, then debuted for the road on the 1983 RD350LCII (31K).
HOW DOES IT WORK?
YPVS alters the height of the exhaust port via a servo-controlled peg that rotates fully open at high rpm for maximum performance, then closes again at low rpm for optimum torque. Simple yet brilliant.
DOHC
WHAT DOES IT MEAN?
Dual Overhead Camshaft
WHAT IS IT?
Two cams; one for inlet, the other for exhaust. When Kawasaki emblazoned the letters DOHC on to the engine cases of its seminal Z1 900 back in ‘72, it was not only a statement of intent, but the way forward for all future superbikes.
HOW DOES IT WORK?
Two camshafts are better than one. A twin cam top-end allows the inlet and exhaust valves to be spread at a greater angle than in an SOHC set up. This gives superior gas flow and optimal spark plug positioning,both of which increase performance.
