Really fast idle

Discussion in '2-Stroke Engines' started by phillyguy, Sep 22, 2007.

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  1. phillyguy

    phillyguy Guest

    Howdy fellas, I've been lurking around here since I put my bike together in march and now I have a question hehe. I have an 80cc chinese motor. So I couldn't start up the other day so I figured it was a good time to replace my wash rag exhaust gasket, seal the leak I had on the float bowl, and put an O- ring in the intake. So I did that checked for a spark and was ready to go. So I mixed 4 oz of oil to a gallon mixed really well 32:1 I think which is what I've been using all summer and she fired right up on the first try. It' runs really good under a load probably as good as it ever has but when I pull the clutch the idle is screaming fast, the idle screw doesn't have any effect. It's so fast and so loud that I have to kill it right away because something is wrong hehe and I'm afraid it's going to explode. The fuel was mixed really well and it was a fresh can of gas and oil so I don't think it's lean (it was slightly more than a gallon of gas but not by much). The slide in my carb doesn't have the smoothest action and I was leaning toward maybe it was getting hung up on the barrel and not completely descending? Oh and I have the needle set on the second from the top I've always had it there. Any ideas? I was going to lightly sand the barrel and the slide and see if that helps at all. I drained the gas and added another ounce of oil just to be on the safe side.

  2. azbill

    azbill Active Member

    fast idle usually spells intake leak
    if you added a o-ring, push hard on carb so it seals to the rubber
  3. gone_fishin

    gone_fishin Guest

    you may be on the right tack, sounds like the slide might be sticking...see the "MBc owners' manual" section about carby assembly...the top cap may be too tight causing the slide to stick up high.
  4. rcjunkie

    rcjunkie Guest

    Check following:
    Carb slide
    cable slack...cable may be too taught and not allow slide to return to fully seated position.
    air leaks
    too lean mixture will cause high idle from air leak, needle clip setting, plugged main jet.
    stuck throttle
  5. phillyguy

    phillyguy Guest

    It was an air leak around the intake. I jammed an empty soda bottle with the cap on between the downtube and the back of the carb to put pressure on the o-ring and then tightened it up. Thanks for the help.