Compression for 1990 Evinrude XP 150

[marty5030]

I am buying a 1990 Champion with this Evinrude XP 150 on it. Owner says runs well and no problems. I had it compressioned checked and found that 2 cylinders had 95, 2 more had 90, 1 had a 100, and 1 lower cyl had an 85.
One mechanic thinks this is just a tired motor and should be fine. I am not sure if motor was at temperature or decarbed recently. Also this was done 6 years ago by owner with very similar numbers.

Any help would be awesome...hopefully this will be my first bass boat unless these numbers are not good.

 

[ob]

Re: Compression for 1990 Evinrude XP 150

I might be a little concerned with the 85 psi hole,however readings in the mid 90's to low 100's are typical on V-6 carbed two stroke John/Rudes.Another factor is the procedure used in obtaining the numbers you posted and the accuracy of the compression guage.

See if the guy is willing to perform a decarb on said engine and perform another test if you're concerned.

 

[MASTER Brian]

Re: Compression for 1990 Evinrude XP 150

I'd also suggest the decarb. I have a similar boat, mine is an 86 Ranger with an XP 150 on it. It ran great when I bought it and didn't do a compression test, but later I lost a cylinder, the others were all at 90 psi +/-.

I don't feel a compression test at time of purchase would have revealed anything as it ran fine for about 2 months before going down. I do think that a decarb might have kept the rings from sticking and later breaking, but I didn't know about it at the time. Looking back, sticking rings were what caused my occasional, but not frequent loss of power 2 times before she died.

Another thing, I'm not sure an expensive gauge would show much. It might give higher readings, but the main thing is that they are all w/in 10% of each other. If you are concerned about stuck rings causing low compression, I've heard of putting a tablespoon or so of oil in the cylinder followed by a compression check and seeing if it comes back up.

 

[marty5030]

Re: Compression for 1990 Evinrude XP 150

ok, thanks for all the info!!!