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  1. #1
    Stop Obama Express
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    96 XP engine wouldnt turn off...

    Pulled the ski out of the water to get ready to head home. Fired it up on the trailer to blow the water out of it and gave it two quick rev's. The second time, the engine would not rev down so i pulled the DESS key and turn the fuel selector off. IT KEPT RUNNING AT HIGH RPM'S!! I pulled the plug wires as well and just waited a minute till it died from lack of Fuel i think. It finally did die but WHY DID IT DO THAT?!?!

    BTW, it did fire back up and turn off like it was supposed to twice after that.


  2. #2
    96XPSS's Avatar
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    This is called lean rev glow-plugging. The engine gets lean, (when it doesn't rev down after a short wot burst), and keeps revving. The spark plug electrode is now orange-hot, and the only thing that will kill the engine is more fuel. If this ever happens again, simply pull the choke or quickly prime it until it settles.

    You do significant damage to the engine when you allow it to lean-rev. RPMs go through the roof, there isn't sufficient oil available for lubrication, so you drastically shorten bearing life when this happens.

    If it acts like it wants to lean rev again out of the water, your low speed jets are too lean. Going out 1/4 turn may settle it down, but if it still wants to hang at high rpms after revving I'd rejet richer.

    An air leak can cause this symptom too, but it has to be a huge one if your engine is stock.

  3. #3
    Stop Obama Express
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    Yea man it is stock. I turned the fuel off and pull the plug wires and it eventually died after a lil bit. I didnt think of pulling the choke. Im taking it back out today and hopefully it will be ok.

    Do you think I damaged it badly? It did start back up and turn off as it should afterwards. I also pulled the plugs and sprayed alot of fogging oil in the cylinders and turned it over by hand without a problem

  4. #4
    96XPSS's Avatar
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    You'll probably be ok, as 800's can take the most punishment of all the Rotax's.

    It's weird that it did this. I never knew about lean rev until I had 951's. They intentionally jet them too lean on bottom to get emissions, and used the accelerator pump to compensate when accelerating. It does no good for flushing out of the water though, as mine would creep out of control every single time. This is another reason the 951 dies prematurely...I doubt very few have not ever lean revved in their lifetime.

  5. #5
    Stop Obama Express
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    Do you suggest I adjust the air/fuel? It does bogg a little when i go from idle to throttle and then takes off.

    Also... ever since I put on my UMI finger throttle, my idle is alot higher but I like it since it stops it from stalling when I throttle it like it use to.

  6. #6
    96XPSS's Avatar
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    By all means tweak on it! If it bogs a little, it is lean. Go out 1/4 on each (lows are underneath) and see if it helps. When you go richer the idle rpm drops somewhat, so you may have to readjust the idle.

    Is the airbox stock too?

  7. #7
    Stop Obama Express
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    Could you tell me where to look and what to adjust? What direction do I turn it? I've never did it before.

    Yes, the airbox is stock as well.

    EDIT: I found it in the service manual about the high and low speed screws, but which should I adjust first and so on. Very noob to carbs in general.
    Last edited by 240witSR; 07-06-2008 at 12:34 PM.

  8. #8
    flyin' the friendly skies airbornexp's Avatar
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    If you take the stock air box off you will see the "high" screws there little t-bars that are spring loaded
    righty tighty = close = in
    lefty loosie = open = out

  9. #9
    Stop Obama Express
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    ^^ i understand that now but what should I adjust? Low or high?

  10. #10
    Moderator RX951's Avatar
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    you need to adjust the lows. As 96XPSS mentioned, when you open it up, it will richen the mixture and the idle will drop some. Remember you get a baseline of the screws, close them all the way but PLEASE do not over tighten them. close them just until the point of where you feel some resistance. The seats are soft and you do not want to damage them.

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