Im new to this site, I took my bike in to have the valves adjusted and the shop said the valves were good, but there was a pinging noise as if the piston and cylinder need to be replaced. I dont burn smoke out of my pipe and the bike only has about 25 hours on it (2008 yz 450). So I went home and took it apart to check the cylinder walls to find that they are in great shape. I looked all other parts over and found the center of the 3 intake pistons to be brand new. Meaning there was no carbon build up like there was on the outer two pistons. It looks like it has not been opening? I dont know if this is normal or not.