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  1. #1

    Rings or Valves?

    I did a routine compression test today and found the last cyl had 70lbs . the center and fist had 130 140lbs. that last cyl has always been low around 115 120. I also did wet test with 1 oz of 30wt and the last cyl
    jumped up to 180lbs the center was 200 and the first was 200 also.
    so what do you guys think rings or valves? Im guessing rings.

  2. #2
    King_Of_Fun's Avatar
    Join Date
    Jul 2007
    Catawba Island, Ohio
    If you add oil to the cylinders and the compression goes up, it's the rings amd not the valves... Ron

  3. #3
    Nice! At least I wont have to spend 500+ dollars on just valves! I should porlly change the timing chain too.

  4. #4
    what do you guys think i will spend on parts? Will I have to get the block machined and put new pistons or just slap new rings and go?

  5. #5
    EZ Dock of Long Island Shibby1485's Avatar
    Join Date
    May 2005
    Long Island, NY
    ur gonna have to measure the bore

    an 03 GTX SC... with low compression in a cylinder... u must have some good hours on there... u gonna split cases and re-use old bearings? i'd hope not, do it all while you are in there...

    Full gasket kit
    main bearings
    rod bearings
    balance shaft bearings
    thrust bearings
    head bolts
    rod bolts
    timing chain
    flywheel bolts
    re-ring all three
    measure the bores, for all you know you might be going oversized
    examine the rod in that cylinder (why did only that cylinder low a bit of compression)

    how many hours on this motor?

  6. #6
    If you consider 100 hours a lot than yea its got a lot of hours. This skis has had low compression in that cyl since i bought it @ 65 hours. It had 115 than
    that was last August. It just recently dropped drastically like 3 months ago
    it was still around 110 115 psi. Last month there was this time it made 1 long beep and the rev limiter kicked in and wouldn't let it go past like 3500 rpm.
    I limped it back to shore and checked every thing and it was like almost 2 qts
    low on oil. My gauges are still broke so I cant tell if there are any codes.

  7. #7
    How much do you think all those parts are going to cost?

  8. #8
    King_Of_Fun's Avatar
    Join Date
    Jul 2007
    Catawba Island, Ohio
    You can check the OEM price on If it was me, I would also put in the SCIC forged pistons. But you need to break down the engine to see what's bad, and like Shibby said, you need to measure the bores to see if you need oversized pistons/rings. There was an '03 GTX SC on PPGs site that had low compression on one clylnder - it turned out to be a cracked piston - the weaker cast piston... Ron

  9. #9
    I guess I should get to pulling the motor out. And tearing it down to see wtf is going on in there. What could have gone wrong to cause this to happen? Like I said the compression was kinda low in that cyl when i got it.

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