Ok Ill try to be short, I replace the cases on a rm 125,due to kick start shaft issues. got a case set on ****, swapped all the guts from other engine, just used new cases. well the piston hits the head. seems to go about 20 thousands above top of jug, matching and looking closer to old case it apears someone may have machined down the case by the base gasket??? is this something that gets done?? If so why and how can I make this work??? thanks for any help.