Lost a circlip on the top end of my kids Kx 85. There's a score that runs from the port intake to the top of the cylinder where the head meets. It's not very big, but the compression after this was like 95# because the rings were toast. So is there anyway to repair a slight score without replating? Also, how much compression is going to be lost out the top if a new piston and rings were installed? The scratch/score does not protrude above the surface of the cylinder wall: I put an old piston with rings on it in and it moves very freely up through the cylinder. I'm trying to get my kid to take responsibility for the repairs of his bike (he's 14) and he can't afford a new cylinder right now so if this one can't be used dad's going to have to pony up $$$ for new stuff. Also, any serious risks to running a ball hone through and seeing if it will hold compression with new piston/rings? Thanks. Dennis