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  1. #1

    Gp1200 need the pros to help figure this one out

    ok have a 99 gp1200,full sbt engine last year with carb rebuild,ran like a monster 63mph with a 300lb guy riding it, had the starter bendix freeze up because the gasket on the stator cover was shot and took in water and got the bendix rusted and stuck,pulled the flywheel dropped in new bendix she ran good as new for about 20 minutes,then she would bog now and then at full throttle,almost like the ignition was cutting out,it only happened a few times,but each time i went out it got a little worse,ok last week it got to the point where i was racing a rxt and she just cut right out fully and died,took a while to fire her back up,then the bogging intermittenly all day got the best of me so i took her home and figured it would be either the stator from the rust from the bad gasket or the ignition box either a coil or cdi so i changed out everything,the entire stator cover and flywheel,the entire ignition box with all wiring and put in all new spark plug.she fired right up took her out to the water got on her full throttle and she did it again,ran perfect hit 63.6 on gps then out of nowhere bogged down until i let off the throttle then came right back to full power,when shes on full power she feel perfect until i get this bog that really feels like the overheat sensor is limiting my rpms(changed the overheat sensor also when i did the box and stator) also tried her on reserve and on with the fuel selector and no change
    battery voltage is perfect with brand new agm battery, what could this be?

    really need some help on this one
    Last edited by junny; 09-14-2012 at 05:08 PM.


  2. #2
    Yamaha artisan Cutlass's Avatar
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    First of all, quite riding it until you figure it out. Bogging at WOT can cause some real damage, because it could be going lean.
    But it sounds like its running out of fuel, maybe because the fuel flapper door at the bottom of the sending unit. Read this thread (http://www.greenhulk.net/forums/showthread.php?t=39216)for more info. It talks about the GPR, but the GP1200 has the exact same flapper door problem.

    Otherwise...it also kinda sounds like its seizing...which is REALLY bad. Especially if it is seizing over and over and over again. Check the compression. Hopefully you won't have a problem there.

  3. #3
    its not a seize thats for sure because she does not fully stall,when she starts to bog i let off the throttle and she goes right to idle fine,only once did she stall out,i know what a seize is,its not seizing. kinda hard to stop riding it as thats the only way i have to play trial and error on figuring this out,i got 4 skis but this one is my favorite and i have pretty much tried everything so far but the bog still comes back,i am going to look into this fuel door tho,never heard of that on the gp1200.

    any other ideas? its not ignition because like i said i changed everything electrical so it has to be fuel related right??

  4. #4
    Yamaha artisan Cutlass's Avatar
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    Well as long as its not a lean seize at WOT, then you should be ok to ride it and try things out. And, yes, I think it sounds fuel related. Like talked about in your other thread, start eliminating all the possiblities for fuel starvation. ie, fuel flapper door, fuel filter, fuel tank not venting, fuel system sucking air through the primer, primer tee restricting fuel flow, collapsed fuel lines, and something carb related(like the internal filters are clogged)
    Also if it is fuel starvation (lean), you should be able to pump the primer or closed the choke a bit to richen it back up. That could prove its fuel related unless the bog is because its too rich.

  5. #5
    ok here is some crazyness,took the sending unit out of the tank yup flapper door was warped big time and would not close,took flapper door off like they said to do but i am having a real hard time understanding how this would starve my ski of fuel,anyone care to explain this to me? cant go test drive it today so will have to wait but i really dont think this has anything to do with fuel restriction on the skis

  6. #6
    Yamaha artisan Cutlass's Avatar
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    My understanding is that the flapper warps and no longer opens and closes properly. And that won't let enough fuel into the pickup. And the other problem is that the flapper can seal up against the reserve pickup tube.

  7. #7
    took it for a ride still got a bog, after looking over the flapper and full assembly there is no way the flapper could hinder fuel flow on our gp1200,maybe its different on the gpr. that was a waste of 2 hours work far as i am concerned.

    willing to try any other ideas anyone has?

    i dont think its the carbs because the way it bogs,not like its bogging on 1 cylinder,its like the whole motor looses power so it will have to be all three carbs with a problem correct?

  8. #8
    Flying Scotsman's Avatar
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    When did you replace the fuel filter last ?

  9. #9
    Yamaha artisan Cutlass's Avatar
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    Quote Originally Posted by junny View Post
    that was a waste of 2 hours work far as i am concerned.
    IMO its never a waste of time to try something. It gets you one step closer to solution. I feel its way better to wrench on something. There's only so much diagnostics you can do on the internet.
    Anything else I mentioned ring a bell? Did you try pumping the primer or pulling the choke to richen it up and seeing how the engine reacts to that? Any modifications to the engine, carbs, exhausts??

  10. #10
    fuel filter flows fine,swapped it with one from my other ski. no primer but did try the choke and that did nothing,going bald from pulling my hair out. no engine mods

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