Engine idle problem - hopefully simple fix

Discussion in '2-Stroke Engines' started by cromartie, Jun 19, 2011.

  1. cromartie

    cromartie New Member

    Here is my problem. Just finished this build this morning. Took it out for its maiden run and it seems to accelerate just fine while moving and maintains speed, but as soon as I slow down or try to idle by squeezing the clutch when I stop it dies. I can keep the engine going while squeezing the clutch as long as I keep revving the throttle.

    Here are some pictures of my build. Take note the home-built intake which I'm running until I get the offset one as the stock one wouldn't fit under my frame.

    Top view


    Side view


    Another view






    Gas line (left long until I get offset) ... it does still pitch down and gas is flowing in on a steady trickle like it should.


    Now the questions:

    1) Could the modified intake be causing the problems? Like I said, it runs fine at speed but doesn't idle. Seems to be sealed 100% and I don't see any leaks.

    2) That Chinese choke lever -- down is choke off and up is choke on right? Bike won't stay running with the lever up -- runs with the lever down (as long as throttle is revved up).

    3) Idle screw seems to have no effect??

    4) Kill switch kills engine at speed just fine.

    This kit came from boygofast.. 80cc 2 stroke. Read the forum for similar issues and none of the suggestions seem to work ...

    Thanks for any help.

  2. motorpsycho

    motorpsycho Active Member

    I see several issues with this build.
    first of all, i know that the intake is temporary, but j.b. weld is not the way to do it, and it appears that you just shoved the copper pipe inside the stock intake tube and smeared j.b. weld around the joint. this could cause an air leak which will make your engine run lean. but, as soon as you get the other intake, get rid of that j.b. welded thing.
    second, look at your wire connections. those push together connectors are junk. they will fail over time from vibrations, and they will either break or vibrate apart.
    but, looking at the wire connectors, it looks like the connector with the blue wire is touching the frame on the bottom where the connector is not covered. cut those connectors off, and solder all of you connections, and then put some heat shrink ovet the solder connections.
    the white wire is showing bare wire, and if that bare wire touches anything, it will make the engine shut off. cut the bare wire off the white wire and seal the end closed with heat shrink.

    see that screw on the left side of your carb with the spring around the threads? well, that's the idle screw. if your engine won't idle, turn the screw in (clockwise) and it will raise your idle. if it will not raise your idle, make sure that you have the carb. slide in correctly. the slide (inside the carb that the throttle cable connects to) can go into the carb 2 different ways, but only one way is right.
    the slide will have 2 slots in the sides 180 degree across from each other. one will be a long slot, and one will be a short slot. the long slot gets lined up with a pin that's cast into the inside throat of the carb on the right side. the short slot gets lined up with your idle screw. if you have the long slot lined up with the idle screw, you will not be able to raise the idle no matter how much you screw in the idle screw. on the other hand, if you have the short slot lined up with the pin on the right side, your throttle would be stuck open because the slide will not be able to go all the way down into the carb.
    yes, the choke lever down opens the choke (off), and the choke lever up closes the choke (on).
    Last edited: Jun 19, 2011
    Ollie likes this.
  3. wbuttry

    wbuttry Member

    easiest way i find to make a reliable idle is adjust your cable tenioner on top of carb a little at a time till it stays at a slow idle then you will be fine
  4. atomichurley

    atomichurley Member

    i had the same problem and i fixed it by adjusting my clutch, just pull your clutch lever and lock it with the locking pin and lift the rear wheel off the ground if it starts to spin it means your clutch is not fully disengaging causing the engine to stall and wear your clutch out from slipping
  5. Wahdib

    Wahdib New Member

    I've got the same problem, I still don't understand how to fix it
  6. Purple Haze

    Purple Haze Active Member

    Okay, now I get it. Turn the idle screw in to increase idle speed. Make sure you have the throttle cable adjusted properly.
  7. Wahdib

    Wahdib New Member

    How do I know if the throttle cable is adjusted propperly? What do I need to do to adjust it?