In this category you will find all the valve boxes we can have for your motocross YAMAHA YZ, WR,... in 2 strokes. We propose you original type valve but also VFORCE, RC2 valves in simple or double roof. The choice of valves is extremely important to have an engine that runs perfectly at low and high speed. It is necessary to pay attention to the thickness of the blades, the orientation, the diffusion,..