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Thread: 1988 Excel III trouble

  1. #1
    Junior Member Mini
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    Jan 2010
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    North Branch, Mn
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    Default 1988 Excel III trouble

    Hi all. This is my 1st Yamaha 2 stroke, but my 3rd Yamaha sled. I got this barn find and it has 119 miles on it. The carb was cleaned, I took it for a short ride, then it bogged down & quit. The fan side spark plug was hot as heck & white. The clutch side appeared normal. Any thoughts? This is a very clean sled that actually looks like it had really never been ridden before. I call it my brand new old sled. Thanks.

    Attachment 64873

  2. #2
    Super Moderator Maim's Avatar
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    sudbury on. canada
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    Default

    Crank seal is most likely the culprit as they dry out over time.
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  3. #3
    Senior Member Stock
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    Change out your crank seals and clean your carb again. Make sure the rubber plug in the carb is good. It should be soft and fit snugly. It goes in the middle hole.

  4. #4
    Junior Member Mini
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    Thanks for the reply's.

  5. #5


    Default

    Make sure there is no mouse nest under the engine shroud.

  6. #6
    Junior Member Mini
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    Took the engine out to inspect. The pistons appeared dryer than they should. The gasket was also missing behind the plate that the carb is mounted to and the intake. My guess now is that whoever took the carb out to clean, didn't adjust the oil injection cable to the correct length when they re-assembled it and when the gasket was damaged behind the plate, so they just used some kind of red colored sealer causing not enough oil for lubrication and maybe extra air getting into the recoil side cylinder. I ordered new gaskets, oil lines, & adjusted the oil injection cable. A Yamaha mechanic friend of mine says the crank seals seem to be fine. Hopefully this will be the fix.

  7. #7
    Senior Member Stock
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    Good stuff. Yes I have found the adjustments way out before as well. Carb and fuel train are always the first things I go through. A leaky intake gasket could contribute to the issues you found.

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