How do you adjust the fuel to air ratio on a 2 stroke carbeurator?

Answer 1

Without knowing the year, type/size of carb or bike I'll try and simplify this as much as I can. Usually the more details the better.
Carbureation is simple. It's just the mixing of air and fuel to make an explosive mixture. It's all the variables thrown in that makes things complex.
A basic carburetor (herein shortened to carb.) has 5 parts that can be adjusted; float bowl level, main jet, pilot jet, needle, airscrew. The float bowl level is adjusted by bending the tab on the float arms. The objective here is to raise or lower the fuel level in the bowl. This in turn regulates the amount of fuel entering the air stream. The size of the main jet also regulates the amount of fuel that enters the airstream when the throttle is open. Otherwise the needle blocks the hole in the main jet. The needle also affects the fuel flow. The taper on the needle determines at what point of the throttle opening the fuel begins to flow and how much fuel enters the airstream. The more radical the taper, the faster the fuel/air ratio increases. Also raise the needle in the slide, by putting the C-clip closer to the pointed end, and the fuel/air ratio begins to change sooner. This provides more of a hit when the throttle is opened. The fuel/air mix at idle is determined by the pilot jet and the airscrew. The slide also regulates the rate of airflow within the carb. Other factors that influence carbureation are how well the air filter is maintained, how well the airbox breathes and the type of reeds used on the intake port. Also since an engine uses the seal on the rings to provide suction to draw in air, a properly working top end also has an influence.
Is your brain sore yet ?
Why do you want to change the air/fuel ratio?
Is the bike stuttering sputtering, stalling down on pwer, carboning up, burning excessive oil....or.....????? Let me know maybe we can solve the problem with more info. OK?