Compression Check Numbers 9.5, 15, 25, 35Hp

[Tom_C]

I pick up a compression tester today to check my new to me 1982 35hp. As long as I had it I figure I test my other motors.

Are these numbers good?

1973, 9.5Hp 70psi both.

1981 15Hp 110psi both.

1982 35Hp 150psi top 160psi bottom.

1991 25Hp 115psi both.

 

[EN2]

Re: Compression Check Numbers

Re: Compression Check Numbers

These numbers look good, maybe do a decarb on the 35 and test again.

 

[Tom_C]

Re: Compression Check Numbers

Re: Compression Check Numbers

Thanks EN2, will do.

 

[Mas]

Re: Compression Check Numbers

Re: Compression Check Numbers

1982 35Hp 150psi top 160psi bottom.

Within 10% of each other is the rule...you're OK. A decarb may even them out.

MAS

 

[freddyray21]

Re: Compression Check Numbers

Re: Compression Check Numbers

the 9.5 looks a bit low to me, but if it runs good then it may be fine.

 

[jbjennings]

Re: Compression Check Numbers

Re: Compression Check Numbers

the 35hp actually looks too high to me. I'm wondering if EN2 is suggesting a decarb to get rid of carbon buildup that might be decreasing volume in those cylinder heads and causing abnormally high compression, and that a decarb would solve?
Just wondering,
JBJ

 

[tashasdaddy]

Re: Compression Check Numbers

Re: Compression Check Numbers

the 9.5 is fine, rope start if you get 60 it is good.