Compression depression

[Boss Hawg]

My 86 Sun Tracker project with 1981 115 Johnson--
Checked compression-
100
55
105
103

What do i do now
I was about to put a water pump rebuild on it but now i'm kind of depressed about the whole thing

 

[jhande]

Re: Compression depression

Try doing a wet compression test next.

Add some drops of oil into the 55psi cyclinder and run the test again.

If the cyclinder pressure rises substanially, it probably needs piston rings.

If it doesn't, you'll have to pull the head as it could be a valve, hole in the piston or gasket.

Sorry the news wasn't better.

 

[tx1961whaler]

Re: Compression depression

My 86 Sun Tracker project with 1981 115 Johnson--
Checked compression-
100
55
105
103

What do i do now
I was about to put a water pump rebuild on it but now i'm kind of depressed about the whole thing

Pull the head on the bad side. See if you can tell if anything is wrong (scratched cylinder, blown up piston, etc). If you really, really can't see anything wrong with it, put a new head gasket on it and see if that fixes it.
Post good pics of the cylinder and you'll get opinions.

 

[Bifflefan]

Re: Compression depression

you'll have to pull the head as it could be a valve,

No valves in a 2 stoke, at least not like you are thinking.

 

[jhande]

Re: Compression depression

No valves in a 2 stoke, at least not like you are thinking.

DUH!!! :redface:

Thanks for catching my oop's.

Sometimes my automotive mechanic brain doesn't think before I type.

Sorry...!!!

 

[Fisher freak]

Re: Compression depression

if it is a metal head you should magnaflux it to check for cracks if its an aluminum head dye it. check rings, piston, gaskets, cracks in the cylinder wall, etc. it sounds like a lot but it is, so happy hunting and lots of fish.

 

[Boss Hawg]

Re: Compression depression

Thanks all, guess i'll pull the head today