Engine Trouble 66cc HT Engine won't idle! looking for help! all fellow gearheads

Discussion in '2-Stroke Engines' started by firefaux, Jul 18, 2011.

  1. firefaux

    firefaux New Member

    Recently built my bike with a 66cc HT chinese motor and it ran like a champ for a week until today I noticed it had less torque going up hills and wouldn't idle.
    I don't have a air filter on my carb since my frame is way to small for it to fit, I don't have a fuel filter, and my muffler is a custom muffler for schwinn choppers.

    I think it could be that the exhaust is clogged, but I could be wrong...
    Looking for help! all fellow gear heads

  2. motorpsycho

    motorpsycho Active Member

    Well, no air filter is not a good thing because even the smallest particles of dirt will get sucked into the carb and scratch the cylinder walls causing a loss in compression (over a long period of time).

    The float in the carb could be stuck and the carb could be flooding over into the engine. This will give it too much gas and the engine usually will not idle and it will run like a dog. Smetimes a few gentle taps on the float bowl with a plastic handle screwdriver will get the float un-stuck (if it is stuck)

    Make sure that you don't have the choke in the on position because that will give you the same symptoms.

    If you have a muffler on your exhaust it is possible that it can get clogged up. But if the engine and exhaust are only a week or so old, a clogged muffler probably isn't the problem. It takes a long time for a muffler to clog up, but it can happen.

    What is your fuel-oil ratio at right now? Sometimes if you have way too much oil in the gas you will have the same problem (low power and no idle). They say to run 16:1 for break in, but 20:1 is ok and the engine will run alot better than it will on 16:1. After break in you can go to 32:1, but it's all a matter of trial and error because some engines run good on 32:1 and some don't. Fuel-oil ratios can be a huge debate.

    Another thing that can and has happened on some of these carbs is that the main jet can fall out and be laying in the bottom of the float bowl.
    Pull the carb off, remove the float bowl, and see if the main jet is screwed into the carb or laying in the float bowl.
    If you are running the orignal plug wire that came with the engine, go get an ngk B6HS plug and throw the original one away.
    Do yourself a favor and go get an automotive style spark plug wire with a rubber boot and replace the stock one with it. (You will need the little cap that screws onto the top of the spark plug for an automotive type spark plug boot to snap onto the plug)
    The stock wire will just unscrew fro the cdi box, and you can just screw the bare end of the new wire into it, centering the screw into the center of the wire so it touches the actual wire and not the outer insulation.

    Check all of your wiring because if any bare wire is touching anything metal, you can lose power going to the cdi, resulting in a weak spark, low power and no idle. (or the engine will not run at all)
    If you have something (like a headlight) hooked to the white wire, disconnect it.
    Cut the bare end off of the white wire and cap it off. Having something hooked to the white wire will pull too much voltage from the magneto and give a very weak spark. Having a headlight hooked to the white wire may work for a day or 2, but eventually it will draw too much from the magneto, and the magneto will get weak.

    If you used those cheap push together wire connectors, cut them off and solder all of your wire connections together then cover them with heat shrink (or black electrical tape at the least) and make sure that there are no bare wire touching anything.

    There are a ton of variables to try and figure out what's wrong, and it will take awhiel to narrow the problem down.
    More than likely, it's a simple fix.
  3. firefaux

    firefaux New Member

    Thanks motorpsycho! nice choppers by the way.
    So earlier I took apart the carb like you said and check everything, but it was all in tip top.
    so I took it for a test run and voila! it idles now!
    it is very weird that it start doing that,
    but I think it was because the engine was overheated. I did run it for 30mins straight
    And now that I run it again from a cold start, the idle was A okay. weird...
    can overheating cause the engine not to idle? or maybe some component to cause it not to idle?
    Last edited: Jul 19, 2011
  4. motorpsycho

    motorpsycho Active Member

    No, I'll bet that you had the slide in wrong and you didn't realize it when you pulled it out.
    Then, you slid it back in the correct way because you were paying attention how to put it back in, and now the problem is gone. It's very easy to install the slide wrong and think that it's in right. It's also very easy to correct the problem of the slide being in wrong without even realizing it.

    An overheated engine will be sluggish, but it should still idle.
    the only way an overheated engine won't idle is if it's so hot that the piston seizes in the cylinder (at that point the engine would be junk)
  5. firefaux

    firefaux New Member

    yeah, i think it was the fact that it was overheated because it was super sluggish yesterday. it wouldnt go pass 20 mph on a leveled road (which it easily does normally) and most of all, if i let go of the clutch it'll stall immediately..

    hmmm maybe it was that, combined with a slip in my clutch cable?
  6. motorpsycho

    motorpsycho Active Member

    of corse, of you let the clutch out sithout giving it any throttle, the engine will die.
    you can take off with it from a dead stop by feathering the clutch out and giving it some throttle at the same time(like how you would take off with a motorcycle).
    I do this all the time and i never peddle my bikes.
    it could be that it was too hot, and possibly that your clutch was slipping.