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  1. #1

    1999 GP1200 spark plug electrodes closing up/ why???

    I replaced the engine in this ski last summer and it ran great for 40 hours before 1 plug gap closed. Rode it twice after that/ no probs until this year when it does the same thing. I ran grounds from the battery to the engine but it did it again on different cylinders. I'm going through the carbs now. It is stock but with Boysen reeds and filters. HELP!!


  2. #2
    krispaintballz's Avatar
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    Sounds like a rod bearing problem. Piston is hitting the plug. This is saying that everything was installed properly. Check for up and down piston movement why keeping the crank still. I would think this would cause the problem right away and not after 40 hours. Kinda wierd.

  3. #3
    Yamaha artisan Cutlass's Avatar
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    I've seen this on a snowmobile engine once. One of the crankshaft bearings was coming apart and the debris was getting sucked up into the cylinder, through the ports. It would bounce around and eventually smash the electrode shut. It also made a mess of the head and piston top...as you can imagine.

  4. #4
    Well, the engine is mechanically sound. Will finish the carbs and re-test. I have never seen this type of problem in 20+ years of jet-skiing. Has anybody else seen this type of problems before???

  5. #5
    PolarisNut's Avatar
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    Detonation can close plugs up. What type of fuel are you running? Have any pics of what the plugs look like? How about the piston tops?

  6. #6
    krispaintballz's Avatar
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    Quote Originally Posted by gntim View Post
    Well, the engine is mechanically sound. Will finish the carbs and re-test.

    Are you kidding??!!!!?! I would rip it down and double check everything. Glad your not holding my wallet.

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