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  1. #1

    ADA head GP1200R lower compression than expected?

    I finished installing an ADA head on my GP1200R 00' and the compression is lower than I had expected.

    Could it be the gauge?
    Or the head?

    The domes are 40cc size which according to ADA's site will give 155-160psi for 91 octane fuel

    I'm getting only 135psi on all three cylinders:

    I'm Using the method described in the how to's section (remove pv cable, leave the spark plugs on, open throttle, test on cold engine, etc...) with an ACTRON GAUGE (don't know where my brother got this gauge, perhaps advanced or pepboys?)


  2. #2
    WATER WOODY's Avatar
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    You need a better guage. If you are getting the same on all 3,your ok.

  3. #3
    mrbtd's Avatar
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    Is your battery strong ? Are you holding the throttle open ? Leaving the other plugs in or out ?

  4. #4
    Quote Originally Posted by mrbtd View Post
    Is your battery strong ? Are you holding the throttle open ? Leaving the other plugs in or out ?
    Yes very strong (full charge), Open, Plugs in, PVs Closed

  5. #5
    Moderator RX951's Avatar
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    ditto on the above. I would obtain another compression gauge and do a comparison

  6. #6
    Quote Originally Posted by RX951 View Post
    ditto on the above. I would obtain another compression gauge and do a comparison
    What brand/model of gauge do you recommend?

  7. #7

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    i've never had a proplem with my snap on gauge

  8. #8
    Haven't fallen yet. MJE's Avatar
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    I do compression tests with plugs out personally.

  9. #9
    Haven't fallen yet. MJE's Avatar
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    Quote Originally Posted by gpr2000 View Post
    i've never had a proplem with my snap on gauge
    doesnt matter if its a snap-on...calibration is required...its why lifetime warranty companies like sears, snap on...don't provide lifetime warranty on things such as your gauge.

  10. #10
    WATER WOODY's Avatar
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    Quote Originally Posted by MJE View Post
    I do compression tests with plugs out personally.
    I do my tests with all plugs out,and throttle wide open.

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