My 250 has low comp about 40lbs won't run. Opened it up ,head and piston looked good. Replaced the piston and rings new gasket. Same problem. Sprayed motor with soapy water turned it over didn't see any leaks. Any ideas
Thank you

 

Doesn't do any good just replacing a stock piston in a worn cylinder bore usually. Have the cylinder measured for the next over size needed as Wiseco,etc has pistons from stock all the way to 2mm over stock size.Then the cylinder has to be bored and honed to the piston. If you happened to have had a new over size piston installed and still no start,usually it's the crank seals that is if you have good spark,compression and good fuel supply.

 

Good point. I'll check cylinder bore next.
Thank you