| 40cc engine doesnt fully uncover exhuast port but 49cc does!
Facinatiting! Just discoverd this when I was playing about with my enigines seing if there is any other ways to tell if your bike is 40cc or 49cc.
In the 40cc engine the piston doesnt go fully down uncovering the hole exhuast port. There is about a mm more it should go down. This making the exhuast port smaller. This is problebly why RD Said in the top "Want your cag engine quicker?" To make it bigger becuase of this.
But in the 49cc engine its all go! It uncovers the hole exhuast port! | 
