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Cylinder Compression

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smsscuba

New member
"I recently purchased a mid 80

"I recently purchased a mid 80`s Mariner 40M,I have not run her as of yet.I measured the compression of both cylinders cold and found the following results:

Cylinder 1~ 140psi
Cylinder 2~ 138psi

The question asked, are these results ok for this outboard or do they need to be of a higher pressure?"
 
From what I have read and been

From what I have read and been told they used to say as long as there is no more than 15psi difference they were good but now they say no more than 20%. I have never heard of any certain specs except for some saying you want it at least around 100psi. My book says to check them warm but I'd think you are in good shape. Hope this helps until someone with more knowledge can answer.
 
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