KTM big bore

When we did the initial develpoment on the 450cc conversion, we used the 520 cylinder, head gasket, and contracted J&E to make a 95mm piston to fit the 520's cylinder and the 400's connecting rod. If you install the 520 piston and cylinder, the piston won't come up to the top of the cylinder and the compression will be low and the engine will run flatter than a 400. The difference is in the rod lengths and thats why we had to make a special piston. I won't sell the piston only, just the kit. But Thumper Racing sells the 95mm piston with a flat top so you don't have to modify the head's combustion chamber like in my kit.