Motorcycle Repair: Motorcycle Carburetor, motorcycle carburetor, fuel mixture

Question
I have a question about a 1982 CM250 engine. I know its not a cbr1000 but bill is gone and i just want your opinion. The old carb was junk so i got a 30mm Chinese OKO carb and it runs rich even with the fuel screw all the way in. Does this mean i need a bigger carb? Im confused because with a bigger carb doesn't it let more air in? Anyway just let me know what you think and if you have a suggestion for a better carb let me know. (PS im never buying one of these Chinese carbs AGAIN!!)

Answer
The mixture is only regulated by the fuel mixture screw at idle.  The rest of it is adjusted through jet sizing and needle height.  Us a smaller jet to get less fuel into the carb throat.  Do not change carb size.  Should have bought a Honda replacement or a used carb...

Good luck,  Jan