Engine idle way too high. please advise!

Discussion in '2-Stroke Engines' started by kennessey, Apr 24, 2010.

  1. kennessey

    kennessey New Member


    New to the forum. Tried searching "adjusting idle" in the forum a few times with different terms but had little success... sorry if I am repeating an issue.

    Installed a 66/80cc Skyhawk for the first time yesterday. While I am technically up and running, engine needs some fine tuning... specifically engine idle. The problem is the only way I can control the RMP's at all is by choking the engine. I actually can't fully disengage the choke because when I do the motor run's full speed. If I pull clutch lever in (disengage clutch) engine red lines (for lack of better terms). I have tried adjusting the air/fuel mixture screw (directions recommend 3.5 rotations from totally closed) but this does nothing at all. I have tried several air/fuel screw variations even totally tightened all resulting in the engine idling the same...full speed.

    Secondly, I am getting a small drip from the bottom of the carb (there is a small screw there). Albiet very slow... it is consistent and I am not sure if it is related to the idle issue.

    I am attaching 2 pics. One is air/fuel screw I have been messing with (which seemingly does nothing at all) and the other is a screw at the very bottom of the carb where the drip is.

    ALSO - Because of the frame the engine has been mounted at a slight angle which also may be affecting things.

    Please help me get this under control before I throw a rod into my nugget pouch.


    Attached Files:

  2. kennessey

    kennessey New Member

    Found similar posts and figured it out...

  3. Chris Crew

    Chris Crew Member

    found an air leak did you?
  4. 5-7HEAVEN

    5-7HEAVEN Guest

    It could be a short throttle cable, or the housing is too long.

    When I swapped engines from Mitsubishi to Tanaka, the Mits throttle cable was too short. I had to "nibble" off about 1/4 inch from the housing at the handlebar end. Then the new engine was able to drop engine speed.

    First thing to do is to disconnect throttle cable from the lever at the handlebar. If engine rpm drops down, then maybe the throttle cable needs attention.

    If engine speed remains the same, look elsewhere.
  5. StrontiumEthics

    StrontiumEthics Motored Bikes Sponsor

    Here are some possible problems:

    1. Engine is slanted so the carb is slanted giving you incorrect amount of fuel to engine ( Try to pick up the front of bike to equilize engine while it is running)

    2. Throttle cable maybe to tight (lower all cable tighteners)

    3. Airleak somewhere ( Make sure all screws are tight, make sure area where carb and intake Mani meets is not leaking)

    4. Look into adjusting your Eclip on your carb

    Overall, I that there are two problems. And airleak (Since you said when you have the choke engaged rpm's go down, and a fuel problem (Engine is getting a ton of fuel somehow to be reving so much)
  6. StrontiumEthics

    StrontiumEthics Motored Bikes Sponsor

  7. kennessey

    kennessey New Member

    Thanks for the great ideas. It turns out that the male end of the throttle cable wasn't totally seated in the female housing on the handle bar, it was caught on the side of the housing which in turn wouldn't allow carb to fully close (so simple:shout:). Once properly seated idle adjustment was easy with air/fuel screw. Glad it happened though...now I am skilled in the art of disassembling and reassembling the carb which I am sure will prove useful.

    Oh yeah...spent about 5 hours riding today and its official...i'm addicted.

    Thanks again for your ideas!!
  8. StrontiumEthics

    StrontiumEthics Motored Bikes Sponsor

    Wow! Thats GREAT NEWS! Congrats. The greatest thing about making mistake with the engines is that you get a chance to fully understand how they work! Hence your aquired knowledge of the Carburators! :tt1:
  9. AussieSteve

    AussieSteve Active Member

    kennessy, the screw on the LHS of the carb is the idle-speed screw, not an air/fuel mixture screw. It merely raises or lowers the slide.
    These NT carbs don't have an idle mixture screw.
  10. tskrem

    tskrem Member

    ur bike is awsome, that is what i wanted to do!
  11. I have a similar, but more concerning issue. when my engine is at idle, the RPM's fluctuate, as if im putting slight pressure on the throttle, then releasing it. also, when i engage the clutch like normal, the engine acts like its either getting bogged down, or its not getting enough fuel, and tries to die. often, it succeeds.
  12. Seely122

    Seely122 Guest

    You may need to adjust the idle screw I was having that problem too