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  1. #1

    Need Help Desperatly

    I have a 96 seadoo with the 787 2 stroke in it. The previous owner had an R&D race kit put on. Aftermarket heads exaust and air filters. My problem is that the engine will rev to full 8000 rpms on the trailer it will idle well on the trailer and once in the water it tops out at 4500 rpms and will not go any more. I have tried everything that I know to do. I just had the carbs rebuilt. I have replaced the grey tempo fuel lines (before the carbs were rebuilt) We replaced the exaust reed valves. We broke down all the exaust expansion chambers and muffler to see if anything was clogged. I know fuel is getting to the carbs, however, even when I frantically pump the primer knob there is no going past 4500 rpms. Since the ski is so old I am having a tough time finding someone that is willing to fix it. I have spent countless hours on this machine it hasn't ran right for 3 summers now I am at the end of my rope with this watercraft. Any ideas on what the problem might be would be muuuuuccchh appreciated.
    Thanks for everyones time.

  2. #2

    Join Date
    Jul 2005
    I'm not sure you actually know what engine is in the ski, because you wrote:

    "We replaced the exaust reed valves."

    no such part on your 787, perhaps you have a 951 that was installed in your 96xp?


  3. #3
    flyin' the friendly skies airbornexp's Avatar
    Join Date
    Aug 2007
    Mahomet, Il. USA
    Quote Originally Posted by TLR View Post
    I'm not sure you actually know what engine is in the ski, because you wrote:

    "We replaced the exaust reed valves."

    no such part on your 787, perhaps you have a 951 that was installed in your 96xp?

    +1 if you cant identify it shoot us a pic so we can help you

  4. #4
    96XPSS's Avatar
    Join Date
    Feb 2006
    Warner Robins, GA Home of the 2007 All-Star Little League World Champions!
    Post pics of what you have. Give us specifics in carb jetting.

    You may be throwing some R&D stuff away, but would you rather throw the ski away, or a few inferior aftermarket parts?

  5. #5
    sorry, I meant rave valves.

  6. #6
    aseymore aseymore's Avatar
    Join Date
    Aug 2008
    Have you tried running it with the fuel selector on reserve? The fuel selector valves are bad about getting stopped up.

  7. #7
    sounds like a fuel issue make sure check valves in fuel circuit are working and that the filler neck on the gas tank is not cracked at the base

  8. #8
    Check your Water Control Valve Bellows on top of the WaterBox. Chances are the metal clip holding the lower part of the Bellows tight has rusted and the two prongs have poked a hole in the underside of the Bellows.
    This, in effect will cause the Water Injection System to flood your Mid-Pipe water Injector and cause the symptoms you describe. That damn clip *should* have been made of Stainless Steel. Some people use a very thin Tye Wrap in it's place. Replace the Bellows though, repairs in this area wont hold. Look for a *very* small hole in the underside....

    Let us know how this works out.

    8000rpm on a 787 ?!? Tht's scream'in bud !


  9. #9
    David thanks for the advice. I am checking into that. I had a problem 2 seasons ago with the ski. The 2" exaust hose that connects the exaust chambers to the water box was getting a hole blown in it after a few minutes of being on the water. I thought that it might be the water valve so I replaced it with a new one. I removed, went through, and cleaned all the water supply hoses that fixed the problem of the hole in the exaust hose, and my ski ran great for one day after I did this which was the last day of the season I had it out. Then I winterized and the next time I went to take it out I encountered the problem I have now. Today I removed the valve to examine it and did some tests on it. I noticed that no matter what position the valve is in, water comes out of the bottom (the threaded part that feeds the water box) Is the valve supposed to constantly provide water to the waterbox? Or is this something that the valve should control? The valve does seem to be controlling the output flow to the exaust pipe coming off the engine. Any more insight would be appreciated.

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