Engine compression

[Prof T]

Ran a compression check on my 1985 well used 90 evinrude. 92-95 lbs on all 4 cylinders w/ engine warm, all plugs out and throttle closed. Now I read I should have had that open, but bottom line is even though they are lower than I'd like, they are even (critical for a smooth running engine).

 

This motor has never let me down, has a negligible resale or trade value, but still does the job. I can't find a reasonable newer used motor and hesitate to put a new motor on a 30 year old boat.

 

So here's my question.....what compression is considered too low? This motor still starts easily and powers to boat as it should.

[devoknevo]

^{As long as it runs ok, don't worry about it.} 

[Chas0218]

Those old johnnyrudes sometimes had low compression long as they are the same across the board you are fine. It could be the compression tester reading low. Either way if she is running fine then you're good. I need to check my timing underway this year I haven't checked it since I owned it but she still pushes the old 23' boat 38mph. I'm afraid to check the compression I don't want to know if I have a low cylinder. 

 

Is yours cold blooded like mine? She starts hard and does a stutter every once and a while at idle but once you open her up she runs like a raped date.

 

Mine is an 1988 150 VRO

Edited April 18, 2016 by Chas0218

[Prof T]

Mine doesn't start bad but they are known to have weak float needles and want to flood a little while at rest. Especially noticeable if the motor is trimmed all the way down.

 

If I remember to trim it up somewhat when I shut it down, she'll start just fine on the re-start. It's a VRO 2, but I've gone to mixing my own @ 50:1 as I troll on a kicker. If I forget and leave it trimmed down, she'll throw a beautiful blue cloud on the re-start.

 

Two stroke heaven--but I feel comfortable that she's well lubed. I think it has a lot to do with why I'm still able to run a 30 year old motor.

 

Did the compression test to see if it was worth a carb re-build. Think I will.

Edited April 18, 2016 by Prof T

[Chas0218]

Yeah I would, I get that nice puff of blue on every startup too.