Tell me what you think of my compression numbers.

[SigSaurP229]

I bought a project boat knowing it was a project boat feel free to see my thread in the resto forum. I didn't check compression before I purchased the boat all I did was turn the flywheel by hand to make sure that the motor wasn't locked up.

Today I finally got to check compression on the motor.

1981 Evinrude 115 hp.

Cyl#1 120 psi
Cyl#2 120 psi
Cyl#3 116 psi
Cyl#4 110 psi


Obviously I am a little concerned about Cylinder 4 it isn't horrible does it warrant pulling the head to take a look?

I wasn't able to properly run a compression as I couldn't get the motor warm and it wasn't lubricated it at all. So what do you all think the best way to approach it is.

Actually that is the first time the starter has even spun on the motor in at least 6 years.

 

[rrw]

Re: Tell me what you think of my compression numbers.

Hi, I would do a decarb and check again. If its still low, I doubt you'll have any issues. My 88 v4 is at 120,120,115&90, it has a scored cylinder. it starts a little hard and runs pretty bad at low end, but runs really well mid to wot, that's with a 30 psi difference or about 25%, you're less than 10%.

 

[boobie]

Re: Tell me what you think of my compression numbers.

Do the decarb on it when you get it running. Those numbers you got on the compression aren't that bad.

 

[Tim Frank]

Re: Tell me what you think of my compression numbers.

I bought a project boat knowing it was a project boat feel free to see my thread in the resto forum. I didn't check compression before I purchased the boat all I did was turn the flywheel by hand to make sure that the motor wasn't locked up.

Today I finally got to check compression on the motor.

1981 Evinrude 115 hp.

Cyl#1 120 psi
Cyl#2 120 psi
Cyl#3 116 psi
Cyl#4 110 psi


Obviously I am a little concerned about Cylinder 4 it isn't horrible does it warrant pulling the head to take a look?

Your average is 116 and the others are within 5%....
I'd say you are fine.

 

[JB]

Re: Tell me what you think of my compression numbers.

What Tim said. Your total span is less that 10%. Quit fretting and go fishing.