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  1. #1

    1999 Seadoo GTX LTD Compression Low?

    My mechanic told me my compression was 120 in both. That seems a bit low. Will it last another season of 30 hours or so? What does a top end cost? Thanks in advance!


  2. #2
    Myself's Avatar
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    Sounds just about right for a 951. If it's running good and still hitting about 6800 rpm's don't worry about it.

  3. #3

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    You could say they both have 80, and I'd say you are probably OK. Unless the gauge was just calibrated, or just off the Snap on or Mac truck, don't trust it. Look at the difference between the cylinders. If one is 130 and the other is 150, then you have a problem.

  4. #4
    You ask 10 different people you get 10 different answers. I was just told by an engine builder that 120 per cylinder (which is exactly what mine has as well), is weak and in need of a top end very minimum, if not a complete rebuild. I just went and looked at a mint 98 XP and passed as it pulled 120 and 116.

    Yet others on here say 120 is perfectly acceptable. I know my (Snap on) gauge is accurate as my 787 pulls 150 on both cylinders. I personally think the 951's always read low.

  5. #5
    Thanks everyone for the info. I knew I would get an array of answers haha Both cylinders are 120,so at least that is positive. It runs hard and rpms are around 6700.Ill run her this year as always,and do a new top end in the fall.What will that set me back you think?Thanks again everyone

  6. #6
    If done yourself figure 400 bucks for a pro x setup through fullbore.

  7. #7
    ilovemyskidoo's Avatar
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    These 951 engines new out of the box have 150psi, I just tested mine and it read 135psi with a known good snap on tester. Is 120psi bad? No not at alll. Is it about mid way threw its life expectancy? yes. Anything under 105psi needs a top end.

  8. #8
    Quote Originally Posted by ilovemyskidoo View Post
    These 951 engines new out of the box have 150psi, I just tested mine and it read 135psi with a known good snap on tester. Is 120psi bad? No not at alll. Is it about mid way threw its life expectancy? yes. Anything under 105psi needs a top end.
    951's out of the box have 135 psi at sea level.

  9. #9
    [QUOTE=Wire4Money;2538825]
    Quote Originally Posted by ilovemyskidoo View Post
    These 951 engines new out of the box have 150psi, I just tested mine and it read 135psi with a known good snap on tester. Is 120psi bad? No not at alll. Is it about mid way threw its life expectancy? yes. Anything under 105psi needs a top end.
    951's out of the box have 135 psi at sea level.
    135 is definitely more like it. I've yet to see a 951 blow anywhere near 150.

    I have yet to find a definitive answer on how much compression you lose with elevation. I'm at 3k' and I was guessing somewhere around 5-7% was probably accurate.

  10. #10
    Kmorningstar_rxp's Avatar
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    For a top end kit it's around 250? And then machine work. Shouldn't be too based, 951 are great motors

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