Late 80's Evinrude 120hp low compression?

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jpinheiro33

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Sep 1, 2008
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Hi, i was just wondering if anyone had any input or suggestions as i just decided to do a leak down test on my motor today and two cylinders on one side were perfect and two on the other were around 10-20 psi leak down. i pulled the heads figuring maybe ide get lucky and it would be the head gasket but it looks to me like the two low compression cylinders have some play in them... There were no noises in the engine and it actually runs excellent but do you think it may go soon or is this amount of leak down ok? is it ok for the cylinders to have a little "play"??? Any help is appreciated. THanks in advance!!!!!
 
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ezeke

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Sep 19, 2003
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Re: Late 80's Evinrude 120hp low compression?

What were the readings on the compression test?
 
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jpinheiro33

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Re: Late 80's Evinrude 120hp low compression?

It was a leak down test and the readings were around 14-16% leak down.
 
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ezeke

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Sep 19, 2003
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12,532
Re: Late 80's Evinrude 120hp low compression?

Leak down tests don't give a lot of useful information on a 2 stroke because of the porting - that's why we use compression tests.

Unless the cylinders and rings are in near-perfect condition and the pistons held exactly in the same correct position for each test, the results of a leak down test will be misleading.
 
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jpinheiro33

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Re: Late 80's Evinrude 120hp low compression?

i did a leak down test bc thats all i have but if i had a compression tester also i would use them both to be safe. *a leak down test on a 2 stroke will tell you the amount of leakage past the rings or head gasket which is just as good as doing a compression test and i dont know if youve ever used one but its very easy to find tdc you hook up the hose and spin the flywheel until you reach your lowest leak down. Ive done it probably a hundred times and it is always accurate.
 
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