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1987 evinrude 110 question

cew

New member
" I recently rebuilt the power

" I recently rebuilt the powerhead on my 110 because it had low compression, and uneven compression. I miked the pistons and checked the cylinder dimensions when rebuilding and they were within wear limits. I therefore used standard rings. When I went to check compression after the rebuild all I can get is about 90 psi on each cylinder. The engine has not run for more than about twenty minutes total yet after the rebuild. (it seems to run fine). My question: do the rings need to "seat" themselves for better compression? I was expecting 100-110 psi. Any thoughts?
Thanks. "
 
" Charles,

I don't thin


" Charles,

I don't think the rings need to seat themselves for better compression. I have rebuilt many powerheads and can say with certainty that the compression always tested fine immediately after the rebuild.

I believe the compression should climb to 100psi on the first four cycles. If it doesn't I start to sweat.

Is it possible that your compression gauge is innaccurate or that you are losing pressure somewhere?

What did the cylinder walls and pistons look like when you opened up the engine?

Did you check the ring gap before installing the rings?

Check the compression with the engine cold and warmed up and note if there is a difference.

I have seen engines with compression in the 90-100psi range that ran well and long, so don't start taking the engine apart yet.

One thing I would say for future reference is that when you rebuild an engine it pays to have it bored for oversized pistons. When you do this the job has to turn out perfect. It costs more but when you consider the service that you will get over a period of time, it is a good investment.

Tony "
 
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