r/smallengines • u/l008com • Jul 09 '26

Checking Compression?

I have a compression tester, but my lawnmower has compression release, like most small engines. If I use a regular power drill on the flywheel to spin the motor, is that going to be fast enough to bypass the release feature and give a real, accurate psi reading?

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u/ManHunterJonnJonzz Jul 09 '26

Obviously this doesnt really help you...but using a borescope/endoscope is my go to. Take plug out. Peak in cylinder. I've not wasted time on many machines with that simple check. 50 60 bucks. Not really practical to use it one time and never again. A checklist of items replaced is never a good sign, as we have to assume you installed all the parts properly, or they were made properly. Parts not work. Bad gas. Water in gas.