4 valve vs 2 valve  By  dmartin95 (Read 4,567 times)

Clank

More valves means smaller holes and smaller distances travelled by the valves meaning less work and stress(force exerted) on the engine translating to more output on the output shaft in theory. Not to sure that you'd see much gain on these little motors. That's how I understand the principal of dual overhead cams. FrankenMech would give the best explanation I would imagine.

stepthrutuner

Since a given volume of fluid (gasses are fluids) travels faster in a smaller diameter tube vs. a larger diameter tube four valves promote superior cylinder filling (volumetric efficiency) and therefore more powerful explosions and more torque. Lighter valves also extend revving ability and take less cam pressure (friction) to operate.

Cyborg

Rich is correct the advantage of 4 valves verses 2 is in the breathing ,,,they simply more air,,,and the valves themselves are lighter with less chance of float at high rpm,,,i've not used a 4 valve head yet but on my next full build it'll be a 4 valver,,and a full balance and blueprint job,,,all of my latest bike builds have been 4v,,,,i've been meaning to start a thread on balancing ,,,i will soon,i've never saw it mentioned on the forum,,,it is very important,,i'm thinking 4 valve balance job lite supercharger we may be talking 20-22hp

Oh i forgot to mention with the 4v breathing so well you don't need as radical of a cam profile so there is even less chance of float