Engine Trouble Engine stalls with choke fully off

Discussion in '2-Stroke Engines' started by intheclear, Oct 6, 2011.

  1. intheclear

    intheclear New Member

    Right now my engine runs best with the choke midway between off and on. If its fully on the engine stalls. The idle is very steady, and I checked the carburetor and exhaust gaskets for leakage. It is a new kit.
    Should the engine be able to run well with the choke fully off?

  2. you are

    not getting enough gas. Probably your idle mixture screw needs to be turned out allowing more fuel.
  3. intheclear

    intheclear New Member

    I'll try that. In my fuel filter there is a thick metal washer inside that is not centered. Does that mean I have a faulty filter?
  4. motorpsycho

    motorpsycho Active Member

    First of all, what carb do you have?
    Yes the engine is supposed to run with the choke fully off (or open).
    If you have an n.t. carb, the choke will be a simple, old style plate that opens and closes at the inlet of the carb. If you have to close the choke, it's telling you that you are getting too much air (making it run too lean). When you close the choke on an n.t. carb you are restricting the amount of air that the carb sucks in. The choke plate actually blocks the carb inlet.
    less air means that it will run rich for cold start ups.
    if it's an n.t., there is no air-fuel adjustment screw...just an idle screw.

    If you have a cns carb. then the choke on this carb works backwards from the n.t. style carb. On the cns carb, when you choke it, you are actually opening the choke (which is just a brass shaft that slides up & down on the side of the carb inlet.) when you open the choke on a cns carb, it allows more gas to be sucked into the carb to make it run richer for cold start ups. more gas added to the air flow will make it run rich for easier cold start ups.
    if it's a cns carb, then yes, there will be an air-fuel adjustment screw that you will have to play with.

    so an n.t. carb...you close the choke to choke it when cold starting, and then open the choke all the way once it's warmed up. it should run excellent with the choke open.

    on the cns carb...you open the choke to choke it when cold starting and then close the choke all the way once it's warmed up. It should run excellent with the choke closed.

    but seriously, 9 times out of 10, if you have to leave the choke 1/2 way on, then you have an air leak somewhere.
    check for air leaks at the carb with a can of starting fluid. Just spray a tiny bit around the carb intake gasket and the carb to intake manifold seal with the engine running.
    If the engine revs up when you spray either of those areas, you found your air leak. also make sure that the top cap on the carb is screwed on straight, all the way and it's hand tight.
    I know that you said that you checked already, but if you use starting fluid, the engine will rev up wherever there's an air leak.

    also, if this is an n.t. carb, remove the air filter housing and look into the carb, Make sure that the choke plate is actually going all the way open and all the way closed when you use the lever.
    If it's a cns carb,remove the air filter housing and look to the right side (i think it's on the right) of the carb opening. Operate the choke, and you should see a brass shaft move up & down every time you use the choke. you want that shaft open to choke it, and closed when it's warmed up. Make sure it goes fully open and fully closed when you use the cable operated lever.
    Last edited: Oct 6, 2011
  5. motorpsycho

    motorpsycho Active Member

    no...as long as gas flows into and out of the filter,it's fine.
    if the engine runs and stays running (with the choke 1/2 on or whatever) it's obviously getting enough gas to keep the float bowl full.
    You can test for flow by removing the fuel line from the carb and opening the fuel shut off valve. Let the gas run through the filter and watch how much goes in and comes out. If the filter is bad, you will have no flow or very little flow coming out of the other end.
    make sure to let the gas line drain into something clean so you can dump the gas back into the tank.
    Last edited: Oct 6, 2011
  6. olow

    olow Member

    :rolleyes7:try a hose without the filter:bowdown::bowdown:
  7. motorpsycho

    motorpsycho Active Member

    the idle mixture screw does not allow more air when you turn it out.
    all the idle adjustment screw does is increase or decrease the idle by moving the carb slide up & down. screw it in, the slide opens and allows more air AND fuel to get sucked into the engine which will make the rpms go up. Screw it out, the slide closes and allows less air AND fuel to get sucked into the engine which will make the rpms go down.
    this has nothing to do with the choke.
  8. Stoltzee

    Stoltzee Member

    Huasheng 142 f
    My bike was doing the same thing, and I rode it that way for about 4 months. Then it sat for a while, and the fuel went bad. I emptied the tank, and put new fuel in, and did a carb cleaning.
    After I got her started I started turning the screw in (lean), until I could get the engine to run as smooth as possible without leaning her out, and the stall subsided. It runs great now, and accelerates better, and smoother.
    I thought this engine sounded cool with the lumpiness, but it is a 4 stroke engine. Now I don't have to run it with the choke slightly on. Look at the spark plug, and see if it's black. That's too rich.