Just finished takeing the bottom end apart on my sons cr 85. This all started a month ago when the bike quit running. Took the cylinder off and found the top of the piston had some metal pieces embedded in it. At first I thought the metal was a piece of the ring but it was all intake. The cylinder head also was pitted. I took the engine out pored a little gas down inside the crank case and tried to flush out any material and nothing came out. Took my dremel tool and smoothed out the cylinder head in the squash band. I didn't take much material just enough to take down the high spots. Checked the rod for free play up and down and felt tight. Put new piston and rings back in and the bike ran fine. Compression was 150 psi. Did the usual break in for the piston and rings. My son took the bike out it ran fine for about 15 minutes and then he came in and couldn't get the bike to start. Took the cylinder off and it had the same size metal pieces in the top of the piston. The ring was still on the piston intake. This time it scratched the side of the cylinder. Sent off the cylinder to Eric to have him look at it and see if he can repair it. I took the case apart tonight and I expected to see some metal shaving or something but nothing. All bearing look good no broken teeth off any gears no broken or missing clips or washers. I am planning on putting new crank shaft bearing and new oil seals. The crank shaft bearing looks and sounds good. I just don't know where the metal is coming from. Both times it looked like pieces of the ring but the ring was all there. Any ideas????????
