Carby Adjusting idle on a Mikuni 18mm Carb?

Discussion in '2-Stroke Engines' started by MotorBikeDevil, Feb 14, 2016.

  1. MotorBikeDevil

    MotorBikeDevil New Member

    Hey guys, I have a slightly different motorized bike. I have no kill switch and the motor turns off everytime i stop. I thought adjusting the idle would keep it going when I stop so i dont have to restart it every 5 minutes. The problem is I dont know how to adjust a idle on a Mikuni 18mm Carb? Can any of you guys tell me how?

  2. HeadSmess

    HeadSmess Well-Known Member

    go back to the stock standard NT if you dont understand how to work on carbs.

    try the screw on the side....

    no, not that one! the other one!

    oh yeah...try adjusting that mixture screw as well. if that doesnt help...well, calls for some fiddling with the idle/lo speed jet.

    of course, there is no point adjusting the lo speed jet and mixture screw until the main jet is correctly sized...

    no-one has yet explained to me why sticking an 18mm bore carb onto a 16mm bore intake manifold is an improvement... maybe you will be the first?
  3. BWB

    BWB Member

    Try that should get ya going in the right direction. FYI HeadSmess they do make 18mm intakes for these carbs and they work well.
  4. HeadSmess

    HeadSmess Well-Known Member

    and then we now stick an 18mm manifold onto a 16mm port opening. still doesnt explain why ? :D

    and of course, have we trimmed that piston skirt so the intake port even gets opened completely, though that sort of affects the induction timing slightly...

    so now we have an 18mm carb on an 18mm intake manifold, and all that gets defeated by the roughly 1cm^2 intake port at the piston...

    just doesnt make sense ;)
    Last edited: Feb 20, 2016
  5. BWB

    BWB Member

    All I know is that with the 18mm carb, 18mm intake, ported jug, trimmed piston, 40mm crank arm, expansion chamber exhaust and improved ignition I go 10+mph faster and get up to speed a hell of a lot faster than stock. To me that makes sense. I don't know what exactly makes it work. It would be cool if I did, but as long as it does I'm good. Who says you can't polish a turd. Ya end up with a shinny turd but I like it.
    45u likes this.