MS310 Compression

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Automender

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Just helping out a friend checking compression on his MS310. I heard it bogging down while cutting a 16 inch maple log with a brand new chain the other day. We got 120 psi on my tester that has a valve at the adapter that screws in the jug. Not sure what the factory compression value is? Any idea of a reasonable compression for a well used saw should be?
 
120 is a touch low, but not out of bounds for a 60cc saw. I have a 55cc saw that pulls in the 130s with a perfect piston and cylinder. If you’re worried, pull the muffler and look for scoring.
 
Fuel lines are weak points on the ms310 family that suck in air as it comes out tank. Buy original Stihl one
 
Thanks for the replies. I was thinking since it didn't have a decompression valve that the compression would be lower from the factory. It actually was 125 not 120 psi plus my gauge is hard to tighten in the cramped sparkplug holes. I need to solder on a extended handle or something to help tighten it.
 

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