Engine Trouble air leak

Discussion in '2-Stroke Engines' started by wan37, Aug 14, 2013.

  1. wan37

    wan37 Member

    Ok I have a 80cc and a 48cc.I have had troubles with the 80cc from the time I mounted it.
    So I swap the good running 48cc to the bike. The only thing I left on was the new speed carb
    that I bought with the 80cc and off set z tube. I had to use the z tube intake on the 48cc
    because of the bike, and now the 48cc runs bad just like the 80cc did. I have a air leak and
    I know it. Really bad when I squeeze the clutch lever it's run away idle. Here's my main question
    how do you find it? The engine is run away so I can't spray nothing on it to see if it idles up to find
    It.
     

  2. Purple Haze

    Purple Haze Active Member

    It's possible that when you changed the intake, you needed to lengthen the cable adjustment. with the longer intake, the cable may be too short, holding the slide up too far to get a low idle. If it is indeed an air leak, a thourough visual inspection will usually locate the problem. Check out the intake welds, maybe tape the welds, those Chinese welders are far from perfect!
     
    wan37 likes this.
  3. wan37

    wan37 Member

    I have another shorter z tube which I like better but the welds leak on it. So I have to use this longer one.I wonder if this will work, I have a centrifugal clutch when I let the clutch out it drop down in idle so should I spray around the intake and carb then or is that too dangerous
     
  4. Purple Haze

    Purple Haze Active Member

    That'll be one wild ride!!! Please don't do that. Try the cable adjustment first, you may not even have an air leak. Also, back the idle screw out so it will be a non-factor.
     
    wan37 likes this.
  5. wan37

    wan37 Member

    I will work on it tonight and will let you know what worked I will try the cable adjustment first then.
     
  6. crassius

    crassius Well-Known Member

    instead of spraying, have you tried smearing heavy grease all over it?
     
  7. wan37

    wan37 Member

    what will the grease do, will it rev up?
     
  8. crassius

    crassius Well-Known Member

    if the grease makes the problem go away, then you've plugged the leak - then just remove grease a bit at a time till the leak comes back
     
  9. wan37

    wan37 Member

    I have it now where it idles a little lower but still not right So I think I'm going to change throttle cable first. I think there was a couple problems. So I know I fix one I tighten the intake at the engine. Now it either welds on intake or where the carb attaches to in take or throttle cable to tight. I'm going to do stuff one at a time until I find it.You guys have been very helpful. Thanks again!!
     
    Last edited: Aug 16, 2013
  10. wan37

    wan37 Member

    update: I have change throttle cable to a new one, still not right. I have it doing this now, Idles good when started with choke on so I turn the choke off and ride it for a couple blocks then if I squeeze the clutch lever it revs real high.So I'm stumped still both throttle cables do the same results. I also tried the tape and then grease around the intake at the welds no such luck there either. I also have o ring it the nt carb too and seal all at the intake to engine with new gasket. I'm just wondering why it does it when the engine warms up I guess?
     
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