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?
 

Backstage

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Trying to find my tape measure
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.
 

cscltd

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Fuel lines are weak points on the ms310 family that suck in air as it comes out tank. Buy original Stihl one
 

Automender

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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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stihltech

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Does it stay up if held by the starter handle? Ditto on the fuel and pulse lines. Pull the muffler and check piston condition.
 

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