Standard Air/Fuel mixture and Idle screw Settings for a Mikilon M96 125-SB

hey there guys and girls ,

i have just brought myself a Mikilon M96 125-SB SuperMoto and i have had a fare few problems to say the least but the most major problem i am having is setting the air/fuel mixture screw correctly .

I was wondering if anyone happens to know the default setting for this ,eg how many turns out to get it sweet ?

cheers

Da Beard

One and a half turns out from fully closed is the usual starting point. Bottom the screw until you feel resistance without forcing it. The end is a delicate needle-like thing.

Back it out counting the full or half turns and that setting should be enough for the engine to start, run and idle fairly well.

Once warm and in neutral, open the throttle smartly and see how it responds. If there's a "gasp" before the revs pick-up make the idle mixture richer.

In the usual, traditional slide carb with the idle screw on the air filter side of the carb, the screw is turned clockwise to richen. This is because in that position it controls air to the idle circuit. That's why they used to be called "air-screw". Turning it clockwise shuts off some air and therefore the idle mix becomes richer.

Do this 1/8 of a turn at the time allowing 5-10 seconds for the mixture to stabilise. Note the effect on the idle speed and the response to that sharp opening of the throttle. The correct setting is when the idle speed reaches a point at its highest and any firther manipulation of the screw makes no difference and the engine responds well to the throttle.

that fantastic thanks ,

just one more question , you dont happen to know how many turns from the screw being fully in to the carb it would take to get it back to factory settings ( the fuel air mixture screw that is ) ?

yet again thanks
da beard

Depends on the carb. What I usually hear is 1.5 to 2.5 turns out from stop. Ultimately, you just have to tune it to what makes your particular engine run best.

Another method is to get the bike warm and have a buddy hold the throttle at around 3k rpm. Adjust the a/f mixture screw out (from stop) until you hear the idle start to drop (indicating mixture is too rich) then back the a/f screw in a little bit...maybe 1/8 or 1/4 turn. When you first back the screw OUT you may notice the idle raising...that's okay. Its when the idle drops that you know you're getting too rich and need to close the a/f screw in a bit. Also, don't take forever to do this method without a strong fan blowing on the engine. If you have easy access to the a/f screw (which Chinese bike may very well have) then it's should take too long.

CC