Air Leak

Discussion in '2-Stroke Engines' started by intheclear, Oct 12, 2011.

  1. intheclear

    intheclear New Member

    Hi.
    I'm pretty sure my carb is bottomed out according to the measurements I took, but this carb is still kind of a loose fit. When I spray starter fluid at the valve, the engine stalls, so this suggests to me there is a leak. The idle is still somewhat high, but I've managed to get it down some. Is there anything I can use to seal the carb, that I could buy from my local hardware store?
    I've experienced the engine running well until I went over a rocky road one day and the idle bumped up again...
    Thanks
    -Greg
     

  2. motorpsycho

    motorpsycho Active Member

    normally if you spray starting fluid at an air leak the engine will rev up, not stall. (unless you spray a whole bunch of it)
    You can try adding an o-ring into the intake side throat of the carb.
    this o'ring slides into the carb, and when the carb is put back onto the intake manifold, the o-ring will seal the gap. just make sure the carb is bottomed out on the intake so the intake is up against the o-ring.
     
  3. Lazieboy

    Lazieboy Member

    I had to do an Extendo carb on my build and had leak used silicone and fixed,but my carb doesnt get hot due to using Hi heat tubing to xtend. do you have an external choke. if so check the tension.
     
  4. motorpsycho

    motorpsycho Active Member

    also check the intake manifold gasket. they are known to blow out quickly.
     
  5. intheclear

    intheclear New Member

    -I bought starting fluid at my local gas station... i didn't spray a lot, I thought...
    just a quick direct burst.

    I think I have an internal choke. Its built into the carb.
    -
    The intake manifold is fine.

    Tomorrow I'll try to get an o-ring at my hardware store. Thanks for the info, people.
     
  6. HeadSmess

    HeadSmess Well-Known Member

    silicone? gasket goo? stag? some paper/cardboard? when theres nothing else handy, thick enamel paint?

    thems my ideas :)

    o-rings need a groove to sit in...

    file the faces of the manifolds flat.

    measure the depth op the socket on the carb. mark the depth on the manifold. make sure it is going full depth...

    squashed bugs, mixed in a paste ;) (or shellac)
     
  7. bideronit13

    bideronit13 Member

    We used to use cork sheet.
    Hope it helps!
     
  8. intheclear

    intheclear New Member

    The o-ring made the idle go down quite a bit, but it still seems a tad bit high. My bike also runs with the choke fully off now, FINALLY. the idle screw doesn't seem to do much to the idle speed though... it stays the same or bogs down. I think my throttle adjustments are fine, it seems to me that the spring snaps it all the way closed... hmm
     
  9. motorpsycho

    motorpsycho Active Member

    are you oisitive that you have the carb slide installed right?
    it can go into the carb 2 different ways, but only one way is correct.
    there's a long slot and a short slot in the slide.
    the short slot goes towards the idle screw and the long slot lines up with a pin that should be on the inside of the carb straight across from the idle screw.
    if you have the long slot lined up with the idle screw, the idle screw will not have anything to seat against to raise / lower the slide to adjust the idle.
    if the long slot is lined up with the idle screw, the skide will drop all the way down into the carb.
    BUT, normally if the slide is in wrong, you will either have no throttle response when you twist the throttle or it will be stuck wide open.
     
  10. intheclear

    intheclear New Member

    I don't think so. When I take the carburetor off and look inside, the idle screw does move the slide incrementally up and down, and also the throttle works very smoothly. I was careful when I installed the slide. However, the idle still is not very sensitive to the screw.
    A few more pieces of info-
    On a cold start, the bike won't idle. I have to turn the screw in to get it to idle.
    Then the engine heats up and the idle runs a bit higher, and I can back the screw out a lot without affecting the idle, and if I go too far, the engine dies.
     
  11. MotorBicycleRacing

    MotorBicycleRacing Well-Known Member

    I have used O rings to seal a lot of NT carbs.

    When the motor is warmed up try full choking the carb
    and see if it kills the motor fast.
    If your intake still has an air leak your motor will run on and not die
    easily.

    Do not use cork as a gasket material for the intake to head gasket.
    Just get some of that grey gasket material from an auto parts store.
     
  12. intheclear

    intheclear New Member

    The motor dies easily when I turn the choke on. I just may be used to lower sounding idles or something.
     
  13. bideronit13

    bideronit13 Member

    Have you checked the jets? I would also check the float because if its stuck youl have these type of issues.
    These symptoms also occure if your not running the hot plug B5HS.
     
  14. intheclear

    intheclear New Member

    I ordered a new spark plug to replace the crappy chinese one. How do you regap a spark plug? The float was fine... but the fuel line wasn't. It was gnarled and I cut it shorter and the engine runs even better now.
     
  15. bideronit13

    bideronit13 Member

    Good to hear
    I dont think there is a gap on there but you can google it
     
  16. MotorBicycleRacing

    MotorBicycleRacing Well-Known Member

    Buy a spark plug gapping tool that is used to measure the gap
    then bend the electrode to open or close the gap.

    NGK B6HS is the best plug for these engines.

    [​IMG]
     
  17. intheclear

    intheclear New Member

  18. HeadSmess

    HeadSmess Well-Known Member

    tap em against the cylinder to close, use ya teeth to widen ;)

    0.5- 1 mm, whatever, its not that critical.

    remember, cheap chinese crud. not italian ferrari.
     
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