How to make a motorbike idle?

Discussion in 'General Questions' started by Mehar, Jun 25, 2014.

  1. Mehar

    Mehar New Member

    Does anyone know how to idle a two stroke motorized bike? Just made a motorbike!

  2. wheelbender6

    wheelbender6 Well-Known Member

    I never had much luck making my China girl idle very long, so I used a thumb throttle. It made it easier to blip the throttle during stops to keep the engine running. Maybe if I had mounted the engine with the float bowl closer to level, it would have idled better.
  3. Ollie

    Ollie Member

    There's a screw on the side of the carburetor that controls idling. The more you screw it in, the faster the engine will idle. A good starting point is to screw it in completely then unscrew it 3.5 turns. After that just start it up and adjust it to what works best. Bear in mind that the engine will idle more easily when it's warmed-up, so you might have to give it a bit of throttle to stop it stalling when you're setting off.
    idler screw.jpg
  4. jaguar

    jaguar Well-Known Member

    those cheap carburetors do not have a separate idle circuit.
    A real carburetor does. It mixes the gas with the air at low air velocity/vacuum.
    Your carb relies on the gas coming up past the needle to crudely mix with the air which it doesn't do a good job of at low air velocity.
    Buy a real carburetor. Click on my signature link to read more.
  5. crassius

    crassius Well-Known Member

    if you set the idle to be smooth when the engine has warmed up for a couple miles, then you'll find it won't idle well when cold - setting it when cold will give too fast an idle when it warms up - take your pick
  6. Fabian

    Fabian Well-Known Member

    So long as the carburettor is jetted correctly and there are no air leaks and the idle speed is set appropriately, the engine (when warmed up) will idle all day long - well, at least my engine will idle all day long without touching the throttle, and that's using a standard NT carburettor.
  7. jaguar

    jaguar Well-Known Member

    In sync with Crassius I say that the problem with "jetting correctly" is that you make it right for idling and then it is wrong for top speed (not to mention mid range)
    No one should be using a NT carb. They just aren't any good because they lack an idle circuit and they aren't fully adjustable.
  8. Fabian

    Fabian Well-Known Member

    Jaguar, i think you must be lacking something if you can't make an NT carburettor operate properly.

    The NT carburettor works satisfactorily if it's set up correctly.
  9. jaguar

    jaguar Well-Known Member

    What I lack is the amateurs inability to discern the difference between jetting that is barely acceptable and spot-on jetting.
  10. Fabian

    Fabian Well-Known Member

    Oh hush now Jaguar. One could almost be forgiven for thinking that you're implying that i don't know how to jet and set up a carburettor to perfection.
  11. jaguar

    jaguar Well-Known Member

    let the gods judge between us
  12. Fabian

    Fabian Well-Known Member

    The gods i can't control and they tend to be unreliable when sacrificing animals in their name, so let the air/fuel ratio be the judge between us.
  13. HeadSmess

    HeadSmess Well-Known Member


    oh my, i think ill print that out and tape it to my wall.

    idle...who the hell NEEDS idle anyway?

    my has to justify the extra expense spent on something useless somehow...