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  1. #1
    JohnCiccarelli's Avatar
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    97 GTX Poor Low Speed Performance.

    This ski starts and runs fine as long as you keep the RPM above 3500. If it drops below this, it bogs until it gets over 3500. I know that rave valves can cause this. I had this problem on a 951 with the rave valves. The solenoid was plugged. On the 800 motor they do not have this solenoid. How do these work differently?

    I have rebuilt the carbs and adjusted the low speed jets with no improvement.

    Any ideas?


  2. #2
    Work Harder, Millions on Wellfare Depend On Us! ultramaxracing05's Avatar
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    I believe this is caused due to a fuel delivery problem, or your not getting a good spark.

    Does it backfire, misses, or anything like that while its bogging down?

  3. #3
    KrunchovXPL-GTX-RX's Avatar
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    The RAVEs are pressure operated on the 787. There is a hole in the base that allows pressure from the engine to push them open.

    It is unlikely that the RAVEs are causing this problem. If they do not function you will lose 3-500 RPM off the top and it will be somewhat less peppy during hard acceleration (unless you REALLY know your boat you may not notice anything other than the loss on top).

    If they are stuck open it will not hit as hard down low (though I doubt it would actually bog).

    As Max said, it sounds like fuel delivery. Does it still have the gray fuel lines? Keep in mind a lean engine will run great once you get it spinning.

    For a while, anyway...

  4. #4
    JohnCiccarelli's Avatar
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    Thanks for the quick reply. I checked the rave valves and the rear one was stuck open. I freed it up and all is fine now.

    Thanks again, John

  5. #5
    Work Harder, Millions on Wellfare Depend On Us! ultramaxracing05's Avatar
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    have you performed a compression test?
    just since the hours were not mentioned. It wouldnt hurt to check it.
    if you have low compression or too much of a difference between each piston,
    I believe it should not be more than %10

  6. #6
    KrunchovXPL-GTX-RX's Avatar
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    It would seem that it will bog if they (or one) is open.

    I have ridden my 951s with the cap off and they would rev up but not like they do with them down. Perhaps the 787 is more sensitive to it.

    Well, good deal. Glad you found it.

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