I hope this is in the right spot and hope this doesn't sound too stupid. I have a 2004 Rm-z 250 that is not running. I tore it down and found the piston ring was out of spec. So I'm in search of a new top end kit. Problem is, the previous owner said something about a big bore kit but didn't look too far into it and when I asked again they didn't know which one. Now what can I measure and what markings can I look at to see if I have one.