I am in the process of getting my 'new to me' 1995 KDX ready for next spring. I pulled the top end apart and found the piston worn and the cylinder worn around the ports but no obvious damage elsewhere. There was a little carbon buildup on the upper lip of the cylinder but a bit of scotch brite cleaned it up with very little effort and there is not much of a ridge left (basically none).
This is my first rebuild and possibly the first rebuild of the bike, the KIPS valves are full of goop and will be requiring alot of attention. The piston that came out was stamped 'B' as was the cylinder. I assume that I can just pop in a dealer or PRO-X, anything I should be aware of? Below is a link to a couple of pics, one of the port side of the piston and one of the ports. I would appreciate any comments or advice you might have. I am going to take the piston and cylinder to the local bike shop for their opinion also but would appreciate the input from some experienced KDX'ers.
If your piston and cylinder are both stamped 'B', then you should use a 'B' sized piston. I think Pro-x is the only company (other than OEM pistons) that make pistons that come in 'A' or 'B' sizes. You could use an 'A' piston, but it would be a little loose and wear alot faster.