A quick check would be to introduce air into the spark plug hole when at top dead center and listen for where the air comes out. It will come out through the carb (bad intake valve), or the tailpipe (bad exhaust valve), or the neighboring cylinder (blown head gasket), or into the crankcase (bad/stuck rings). A lower portion of a two-part compression tester with the quick disconnect that fits your air compressor works good for this. Turn down the pressure on the regulator of your compressor or put a regulator in line if your compressor doesn't have one.
Last edited by 52Carl; 10/01/2013 9:12 PM.
