When I got the ski the only thing it had was the motor and factory pipe. I put in everything else brand new. Before that the motor was sitting for almost 6 years and it had been fully overhauled then.
By restoring the ski I bought new everything that was missing and all oem parts either from the dealer or online.
To test the compression I used a good guage with a fully charged battery. After I restored the ski my mechanic told me the pressure was about 115 but it should go up since the motor has been sitting for a long time. Unfortunately it didn't.
Unfortunately a motor sitting that long with no preceeding love could be damaged. I do agree that you should exhaust your testing options before you rebuild the motor, but there are limited tests and the likelyhood of damage is faily high. The motor could have rust on the cylinder of sitting and immediately damaged itself as soon as you tried to use it. It could have been used a few times beforw it was left to sit and althouh new, could have been poorly built or poorly tuned and been low once it sat. Often skis dont just sit they have some sort of problem that doesnt get fixed, like electrical or carburation, in this case it could have been compression. It also could have been that the rebuild was done incorrectly.
For compression tests I only used a guage. Are there any other tests you suggest I do?
There are no real fancy tests to do. You just need to be sure you are doing the test right. 150/110 would be a clear indication of a damaged cylinder, but 110/115 are close numbers and that could be a symptom of a bad guage, bad battery, improper testing or some other bad component.
You need to make sure the test is done correctly. Good battery, good gauge, good connections. Hold the throttle wide open with the plugs in and wires off and grounded and crank the ski over until the gauge stops climbing, abput 5-10 revolutions.
If the numbers are low, you could test with a different gauge, but a gauge off by 40 psi is less likely than one off by 10 or 20.
The next step would be to remove the cylinder head and visually inspect the cylinders. Any scratch you can catch with a fingernail is too deep. You can also check the crank by turning the piston to a downward motiln and stop before BDC, then hold the crank and push down on the piston, if the piston moves and the crank does not then its indicitive of a bad crank bearing and you should do a full tear down.
With that time on the shelf, unknown reason for it being there, and other possibly history, your best bet is to rebuild that motor. It could be a ticking time bomb with a worst case of a crank rod through a very rare case.
