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  1. #1
    quadzilla's Avatar
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    Unhappy GP1200 problems.

    Needing a little help gentlemen....

    My gp1200 is having some problems.. (completely stock..)

    the problem is that after a very good weekends wavejumping..
    my ski is seriously bogging down out the hole and in the midrange..??
    when the thing gets going all seems fine till..
    i get out the throttle then the bugger just won't get moving again.. then its fine..??? when it gets going..????

    OK... so i've changed the plugs.. they were a little bit black but NOT filthy/caked in crude..!! NEW PLUGS didn't help..??

    NEXT.... i've checked the compression..!!
    first go..#1=112, #2=115, #3=117,
    second go #1=115, #2=117, #3=117,
    so i left it at that thinking thank fcuk its not fubared..!!!

    My next thing will be to swap out the fuel filter..??

    I KNOW its likely gonna be the carbs that need overhauled..!! they've "never" been touched in 80hrs..??

    Anyway Gents looking for ideas/thoughts before i need to pull things apart..
    (can't believe i've now got two ski's misbehavin..!!).......WTF is going on..???

    cheers Gerry...


  2. #2
    jdog800's Avatar
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    almost sounds like your low speed jets could be leaking causing to load up off throttle........when your back on it does it seem to clear up and run good until you are at idle again? I would definatly be thinking about a carb rebuild if it has never been done. Is this the first tank of the season? did you winterize it? Have you made any adjustments?

  3. #3
    jdog800's Avatar
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    another thing to check especially if you jump alot is the idle screw. Try uping the idle just a little bit and see if the problem goes away. I have seen idle screws get worked down so that it causes all kind of misbehaveing low speed problems.

  4. #4
    cheatin' piston popper addicted's Avatar
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    empty out the fuel filter. It is also a water seperator. Also, does the gp have a seperate water drain like the raiders? if so, dump that too. you may have alot of water in the tank.

    alos look for kinked fuel hoses and tank vents.

    A carb reduild or at the very least teardown and inspection are in your immediate future too. It could cost you an engine.

  5. #5
    Moderator OsideBill's Avatar
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    I am leaning towards the fuel circuits too go through everthing could be simple could be involved take it a step at a time starting from the tank check that your flapper door on the gas pick up is not blocking your hoses then remove it so you will not have to worry about it again check the tank vent it should allow air in not out. check the on off reserve valve. change the filter then go into the carbs if you have to could be check valves they are notorious on the 44 SBN carbs. stuck needle maybe flooding it with gas.

  6. #6
    quadzilla's Avatar
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    Thanks for the input so far guys..

    On the tank checkvalve thing.? that's all good.! when i unscrewed the gas cap,
    I got the whooshing air noise..? or more accurately the tank depressurising..??
    also i checked the valve too its all good..

    The water separator is separate to the fuel filter, its good to go too.. NO water in there..!

    the idle screw could be an idea to look at, i've had the air box lid off and checked the choke plates were not loose/disconnected they're ok..! what i did notice was that the throttle butterflies looked closed quite tight..??? they're synchronized alright through..!
    should these be slightly open the way you'd have set up carbs on cars with a 3/8th drill bit for example..??

    anyway again thanks for the input gents.. i'll get in about it again tonight/tomorrow..
    starting at the tank end...!!!

    Oh-yeah hows those compression figures looking..?? low or alright..???

    cheers Gerry..

  7. #7
    DAGO RACING CREW 97GPSLEEPER's Avatar
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    I agree with all of the other suggestions as well. The compression is in the good range. Stock compression at sea level is 125. The battery must be fully charged and the throttle held open and only take the plug out in the cylinder you are testing to get an accurate compression reading.

  8. #8
    Mongoose's Avatar
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    Im sure it's fuel related.
    If it happened after a days jumping, I would say you picked up some chit in the lines.
    You could try and turn the fuel knob to reserve to see if it still does it.
    That way, you will eliminate one potential problem.
    How many hours on the carbs? might be time for a rebuild
    It might be some crud in the carb filters. If your'e going to get in there and clean them out, I would change the check valves as well. Creased valves make starting the ski harder, and it's not the best starter in the world when everything is good!

  9. #9
    Flying Scotsman's Avatar
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    Buterflies will be open slightly comp 120 psi stock
    Should be about 3000 rpm out of water 1300-1400 rpm in water.
    Have you got your pulse lines on good no leaks ?

    I KNOW its likely gonna be the carbs that need overhauled..!! they've "never" been touched in 80hrs..??

    Just read that Yank those puppys and rebuild you will find creased check valves at the verry least.
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  10. #10
    quadzilla's Avatar
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    News So Far..

    OK pulled the fuel filter out of this sucker...

    Got To Say there was some amount of "CRAPOLA" in there..!!!
    It looked like somewhere between sand, sawdust or finely ground fibre..??

    Have some pics can't get them to load..?? and that's only from phone camera to my computer..!! D'oh.!!

    Anyway thought.. ok the carbs are coming off..!!
    So i yanked the suckers out.. pulled em to bits.. apart from some dirt though nothing like the SH!T in the filter..
    Carb #3 wasn't too bad no creased/damaged check valves...
    Carb #2 much the same story.. some dirt no damaged check valves...
    Carb #1 now then...?? some really nasty corrosion type stuff going on in there..?? mostly around the diaphragm (jet side)
    so cleaned all this gunk out..!! It also had one creased/damaged check valve which amounted to, two small v shaped dings..
    Now bear with me on this (since my dealer doesn't keep these in stock, talking tues/wed at best to get em in..?????)
    I just pressed it down pretty much flat flipped it over and stuck it back in..????? (i "KNOW" not what you'd recommend)

    Anyway i just built them back up and stuck em on the ski..

    Got the thing outside and fired it up.. sounds much better revs up the way it should/did..

    now here's the thing its only idling at around 13-1500 rpm's on the hose using the stock display/tach..??
    sometimes dropping lower though it never stalled or cutout..???
    Hmmm.. as i type this i'm thinking sh!t do i have an air leak somewhere..???
    The other thing i'm gonna do tomorrow before i get on the water is buy/install a couple of in line fuel filters,
    To catch anymore of this crap that came out the yamaha one..!!
    Whats in these yamaha filters that does the actual filtering..?? could it be that, That's breaking down since its about nine years old..??

    That's all for now Gents.. please feel free to express your feelings on my not waiting on the check valves from my dealer..!!!
    (knob-cheese/dipstick/dickhead..etc.etc)

    Ah... one last thing.. say i was wanting to ditch the stock airbox..??
    Would i have to go to premix.? since i had a look at the riva site and to change to cone type f/a's they seems to only advertise,
    the air filter (f/a's) and carb adapters no factilty to use the oil injection as per the stock airbox system..??
    Or am i really barking up the wrong tree here..??? (Woof-Woof) lmao at my own dopiness here..
    Help/advise really needed on this aspect..!!

    Apologies on the lengthy post here guys & quite possibly dolls or gals..???

    Cheers Gerry

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