[msmcknight]

Hello everyone,

I have a 1997 GP1200 engine that I need to check the compression on. I've never done this and am a bit unsure how to get a good reading.

The issue is that the engine has been removed from the ski, so I need to check the compression on an engine that I cannot start and that has most of the external components removed (ie. flame arrestor, exhaust, etc.).

The last time the engine ran, it ran like a champ, but before I can sell it, I need to be able to tell prospective buyers what the compression is for each cylinder.

Any tips on how to do this would be appreciated. Also, what compression numbers should I expect to see?

Thanks to all in advance,
-Michael

 

[bigair64]

Shouldn't be a problem

Remove all three plugs and hook up compression gage to one cylinder. Hook jumper cable - to anywhere on engine block and + to starter motor terminal. Hook other end of - cable to battery - terminal and touch the other end of the + cable to the + terminal for a second or two which will allow engine to crank sufficiently to register max compression. You should then repeat for the other cylinders. Depending on the pressure gage you are using, you should see about 110psi on all three. Don't be concerned if it is as low as 100psi as long as they are all the same (within 5psi of eachother).

 

[JUST-IN-TIME]

10% of each other, not 5 psi

do it cold
do it warm
do it with a teaspoon of oil

also hold open throttle