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Thread: compression ok?

  1. #1

    compression ok?

    I have a 2004 Polaris Genesis with the fuel injected 1165cc engine. 188 fun hours and still going strong. I checked the compression and got the following numbers;
    mag 125psi
    center 125psi
    pto 119psi
    Is there any need to be concerned about these readings?


  2. #2
    100 MILES OF HEAVEN AND I AM SMACK IN THE MIDDLE KEYZBUM's Avatar
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    Quote Originally Posted by prairie water View Post
    I have a 2004 Polaris Genesis with the fuel injected 1165cc engine. 188 fun hours and still going strong. I checked the compression and got the following numbers;
    mag 125psi
    center 125psi
    pto 119psi
    Is there any need to be concerned about these readings?
    I say those are good
    the limit is 10% between them....not so much as WHAT the number is(now ofcourse this has its low limit also**less than 100 stay away***)
    different comp.guages give differnt number,Who/how it is being done,,,alll factor in
    GOOD TO GO
    mattman

  3. #3
    Click avatar for tech links/info, donation request K447's Avatar
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    Quote Originally Posted by prairie water View Post
    I have a 2004 Polaris Genesis with the fuel injected 1165cc engine. 188 fun hours and still going strong. I checked the compression and got the following numbers;
    mag 125psi
    center 125psi
    pto 119psi
    Is there any need to be concerned about these readings?
    These readings were taken with the throttle held wide open - correct?

    Spark plugs in the other cylinders during testing, or all removed?

    Battery was fresh/well charged?

  4. #4
    uh-oh. I forgot to open the throttle. Will try again this afternoon and post. Please be patient with the new guy.

  5. #5
    OK, here are my revised numbers from my original post.
    Throttle held wide open.
    All 3 plugs removed.
    Battery in good condition.

    Mag 124psi
    Center 122psi
    PTO 116psi

    Should I still feel good about my engine with 188 hours?

  6. #6
    Click avatar for tech links/info, donation request K447's Avatar
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    Quote Originally Posted by prairie water View Post
    mag 125psi
    center 125psi
    pto 119psi
    Quote Originally Posted by prairie water View Post
    ...Mag 124psi
    Center 122psi
    PTO 116psi

    Should I still feel good about my engine with 188 hours?
    That is about a 7 percent variation from highest (125) to lowest (116), and 120+ PSI is in the good range.

    Looks like the top end of your engine is still in fairly good shape.
    Are you happy with the performance and power you have right now?

    10% or greater variation in compression between cylinders is typically considered too much for long term comfort. 5% or less is desirable.
    Last edited by K447; 05-20-2008 at 12:42 AM.

  7. #7
    Thanks for replying K447.
    My little boat snaps to 6800rpm whenever called upon. Always starts right up and never complains about dragging tubes and wakeskaters. Your comments make me feel pretty confident of my engine health. Now if it would just warm up. Northern IL has yet to see any "global warming'.

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