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  1. #1

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    97 GP1200 Frustrated Dilemma

    So heres my issue. 97 GP1200/65U totally bone stock. The issue is it will die out after getting on plane. Sometimes it will shut off but will start right back up again. It will idle fine. When you give it throttle either slow or fast, it will sometimes bog but idle fine and sometimes it will die. Sometimes it will make a good fast run for about a minute and then a loss of power comes over it and it will run at slower speeds for a bit then act up again. Here is what i have done so far. I rebuilt the carbs with Genuine Mikuni kits and verified all the stock jetting was in the proper carb. The turns out on screws are stock spec from the service manual. Pop-off was set to stock specs as well. It is premix at 32:1 with Dominator oil only and all fuel is fresh. Compression is 120 on all 3. it has spark on all 3. 4 out of last 6 times i have removed the carbs and had to replace creased check valves. I thought this was the problem so I did Oside's fuel return drill out with the 105 inline main jet and did the duel fuel supply as well bypassing the fuel selector and adding another fuel filter in the second fuel line. fuel tank always holds pressure as noted by unscrewing the cap. all components are in awesome shape no corrosion on anything as you would expect from a freshwater ski. I think this pretty much covers it. So I need you guys to did deep and help me come up with something else to try or something I overlooked..Thanks

  2. #2

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    Sep 2014
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    Did you check the exhaust chamber and make sure that it is not clogged and possibly overheating?

  3. #3
    butterbean_29512's Avatar
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    Sounds like your fuel tank vent check is stuck. Easy to check. Loosen your gas cap and see if it will go to full power. They do sometimes fail.

  4. #4

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    As above.

    Also... probably not the cause of your problems but 33:1 is WAY to much oil for a stock ski. That's more like a mix for running a new motor in. More oil = less fuel going in the engine = lean mixture. Stock ratio is 50:1 but most guys seem to run around 40:1. I'm in the middle, around 45:1 and I'm big bored, ported, head skimmed....


  5. #5

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    Quote Originally Posted by Raider1200 View Post
    As above.

    Also... probably not the cause of your problems but 33:1 is WAY to much oil for a stock ski. That's more like a mix for running a new motor in. More oil = less fuel going in the engine = lean mixture. Stock ratio is 50:1 but most guys seem to run around 40:1. I'm in the middle, around 45:1 and I'm big bored, ported, head skimmed....
    I was always a little deterred by people going to 50:1 and then hearing stories of seized pistons and rebuilds from being lean. the factory oil pump is like 100 or 200:1 at idle and maxes out at 32: at WOT. so i prep for WOT cuz thats the only way my kids seem to drive them. the minuscule difference of a bit more oil is not enough to create a different fuel mixture to say it would be lean, that is why mixture settings are usually always plus or minus a 1/4 turn. at any rate, I have 2 identical skis, my daughters ski runs like a wet cat all day with no issues at all. my sons ski seems to have the only issue and his has less hours on it than hers. there is something im overlooking with this ski. I m going to check the fuel tank vent tonight. other than that, I ordered all the Mikuni parts to go with Oside's carb jetting recipe for this model and see if that cures it.

  6. #6
    Mpeavler's Avatar
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    65U engines are 50:1 at WOT .., not 32:1
    Oil displaces fuel so at 32:1 your are running the fuel mixture leaner than OEM

  7. #7
    Carbs rebuild

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