the mixture is adjusted ( the main adjustment, and the one you need to be right, at full throttle) by the main jet. it is the small (size of a screw head) brass fitting with a tiny hole in the center screwed into the carb body inside the carb bowl. you canbuy different sizes for different applications also when you receive the parts, youll get a needle. this is has four notches and is adjustable as well. although i (and i think many others) always just put it on the upper notch to make the mixture the leanest. this controls the mixture at less-than-full throttle. read the maxi service manual that someone gave the link to above. you can learn a lot real quick.