This is the carb my 2009 ATA-110D has. Starting with the screw down at the bottom of the bowl which I assume is the bowl drain; Any idea what the one towards the inlet and one at the center are?

 

bottom = bowl drain
middle = idol speed
left near the air filter = fuel/air mixture

I just got done fiddling with these on my Tao Tao 125H, carb is pretty much identical to that one...

 

Upon further review, my 'emissions compliant' 110cc does indeed have the square bowl carb as pictured above, but the mixture screw (towards the air cleaner end) is just a bronze plug! The only thing on it is the idle setting screw! Well.. atleast I verified it lights off and runs like a **** in 20degF temperatures.

Joel

 

Oh.. the other funny 'high-tech' emissions trick they did on mine was drilled the end cap and installed a brass nipple on the air filter housing for a place to terminate the crankcase breather hose. A genuine China quad PCV system.

Joel

 

I would think under the brass plug is a adjustable fuel screw.