I've got a 2001 YZ125. The left side power valve hit the piston ring and caused a nasty gouge in the cylinder wall. I'm not sure on how to adjust the power valve depth. What's the trick to that? This top end had maybe 30-40 hours on it before this happened. Ran great up until it sputtered and died out on the trails. Is a new jug (5MV-11311-00-00) the best way to get the motor back together? Any advice appreciated.