Air mixture screw thingy... I think

Ok, so after many weeks of not being able to ride, I finally have it up and running!!! I have 2 questions.

#1. I was playing with the air mixture screw when my bike was idling. I noticed that if I turn it clockwise the engine starts to rev higher. If I turn it counter-clockwise, it revs lower. My question is what is the best adjustment for the screw and if I have it too tight, will it reck my engine?

#2. My engine starts to make a bbbbbbbbbbbbbbb (not smooth) noise at certain throttle positions. When I twist it some more, it sounds like, mmmmmmmmmm (smooth). What could be going on with the engine? I asked my dad and he said that it is because the engine is out of balance... is this true. If so, how do I fix it?

Thanks,

Ben

1) Makes sense - because that is your idle screw.
2) Allow it to break in and then start adjusting stuff per all the threads here. (Not a matter or turning screws unfortunately)

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1. As stated the idle screw is for SPEED ONLY, not mixture.
2. That sounds about right...without a long winded explanation, a two cycle engine (when properly set up) will run smooth (mmmmm) until it has very little load on it, then it will break into a 4 cycle...( bbbbbbbbb). When you come to a hill, or twist the throttle a little more it will again clear out and run smooth...(mmmmm).

Only when you are really reving it up will it stay "smooth" since it's got a load on it at 30+ mph.

You are fine, ride the thing!

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If it ain't broke, and you mess with it long enough, it will be.

Its easily mistaken for an air bleed screw. An airbleed screw would be perfect for our carbs to fine tune the los end mixture setting.