The kx500 cylinder if not modified can not be bored over as they are plated. I have the same plans for my engine. I do not have any noise and it is fairly powerful, but in about three months I am going to completly overhaul it. I plan on doing the following. New piston, shaved head, new main bearings and seals, v-force reeds and block, new clutch, and check crank clock. The cost is not bad as my motor is stock and 8 years old. It still produces 162psi compression, and I have not really ran it since fixing alot of neglected problems that it had. My advice, if you are going to take the time to take the motor down do it right and the motor will do you right.