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  1. #1
    srjrinc's Avatar
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    Consequences of low compressio on modified GPR

    I have an 01 GPR 1200 with everything on it! Triple Pipes, head, Novis, pump...too much to list. I just happened to take a compression before I was getting ready to take it out for the day.... Cylinder 1 & 2 are about 160 PSI. #3 is at 110.....So my question is what are the possible consequences if I use the ski like this for a while? I will eventually rebuild the top end again. Any thoughts?


  2. #2
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    Well I'm not sure if serious, but sure you can run it and run the risk of buying possibly a new top end, jugs, crank, gaskets, crank seals, and maybe even new cases. If it were my ski I wouldn't even be asking this question but post up pics if you do decide to run it

  3. #3

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    You have to ask yourself, why is #3 at 110? Just more worn than the rest, "maybe" no big deal. BUT, what if it is low because you have damage from an airleak or clogged carb and are running lean? Then you risk meltdown of the piston, possible cyl damage, and even seizure and whatever goes with that: crank damage, bent rod, broken rod, broken cases. I would figure out what was wrong and fix it because you know something is not right. Ignore it at your peril.

    Quote Originally Posted by srjrinc View Post
    I have an 01 GPR 1200 with everything on it! Triple Pipes, head, Novis, pump...too much to list. I just happened to take a compression before I was getting ready to take it out for the day.... Cylinder 1 & 2 are about 160 PSI. #3 is at 110.....So my question is what are the possible consequences if I use the ski like this for a while? I will eventually rebuild the top end again. Any thoughts?

  4. #4

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    [QUOTE=LT1GMC;2126086]You have to ask yourself, why is #3 at 110? Just more worn than the rest, "maybe" no big deal. BUT, what if it is low because you have damage from an airleak or clogged carb and are running lean? Then you risk meltdown of the piston, possible cyl damage, and even seizure and whatever goes with that: crank damage, bent rod, broken rod, broken cases. I would figure out what was wrong and fix it because you know something is not right. Ignore it at your peril.

    +1...Fix it now and not risk doing any other damage that could happen if you continue to run it. It could be something simple and inexpensive to make it right now but who knows if you keep riding. I am going through the same thing with my 1456 triple pipe. You would have never known it had rear cylinder/piston damage when I water tested the ski prior to buying since it ran so strong (83mph) but the #1 & #2 had 150 lbs. and the rear was @ 60!! Plus, there was a tiny hole in the piston...go figure (ha ha). I'm doing a full rebuild so I know the motor is perfect. Whatever you decide to do...make sure you pressure test the motor. This is an easy step that gets skipped a lot and then you have more issues to deal with.

  5. #5
    srjrinc's Avatar
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    Thanks once again for steering me in the right direction.

  6. #6
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    Fix it now...do NOT take that ski back out. If the piston goes kablooey, then you will have more trouble than just low compression. Take the pipes off and get that cylinder off..order new pistons/ring kit from Greenhulk store (cheaper). But you need to find out first, why this cylinder went bad. If it is cylinder 3, the one closest to the rear of the ski, then hopefully you know that the jetting needs to be one size jet up on high speed jet. We always ran #3 richer when running triple pipes. Just like mentioned up above..pressure test everything, including the pipes. #3 pipe is also know to crack and go down before the other two do. Engine pressure check to make sure seals/gaskets are doing their job.

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