95 spx engine low compression

[mistersolo]

Hello,
I picked up a 95 SPX that has been sitting for about 3 years. I'm wondering about the compression. The engine has 90 psi in both cylinders.

I haven't been on the water with it but it starts fine on the trailer. The oil tank was dry and the hull had a bunch of oil in it. I've replaced the oil lines, swapped out the gas and the feed line and have started it with it running on the hose for a couple minutes. There seems to be some dirty oil coming out of the exhaust, but I think that may have been from seepage from sitting a long time and I'm hoping its residual oil that will burn out after a bit of running out on the water.

Because of the low compression, I pulled the head off to inspect the pistons and I expected a bunch of scratches and wear. It looks pretty clean to me and there aren't any scratches that I can catch a nail on and it looks like uniform crosshatching around the cylinders.

I'm not sure what to do next. Does it just need rings and a ball hone, or pistons? There is a mark that says 0,75 on the pistons. I'm up for suggestions.

Thanks,

John

 

[snikwad003]

With bores like that I'd go ahead and do the carbs maybe put a little oil in the fuel ride it kinda like a break in and I'd bet the compression comes up

 

[Paul Bretz]

First thing i do when checking compression is always compare with another compression tester to make sure first tester isnt bad. Somebody else will chime in but im not sure that it would even run with only 90 psi.

 

[mwat65]

Yes , I would try another tester like Paul said. Make sure your battery is fully charged and hold the throttle wide open.

 

[mistersolo]

I was suspect of my brand new high quality Harbor Freight Compression tester (roll eyes). Holding the throttle open changed the reading from 85 to 90 psi. I used the loaner program from O'reilly and tried out two other testers. One didn't even work and the other one would kinda work if I held the hose just right and it matched my 90 psi. I did test the Harbor Freight tester against the gage on my compressor and the pressures matched.

I think I will get it out on the water and see what it does and then recheck the compression.

If getting it out on the water doesn't bring the compression up or if it feels like a dog, I will be tempted to replace just the rings and run a flex hone in the bores. My guess would be that the rings weren't properly broken in. I suppose it could be a timing issue as well. Who knows?

 

[mikidymac]

It actually looks really good. If it is actually 90 psi it will not run or start in the water. I would give it a try as long as you service the carbs and fuel system first.