i have one on my 4x4 quad,tuning as read in manual, the smallest hole on a daj is the richest setting,the largest hole is the leanest setting,remember to loosen lock down screw before turning dial,as far as jet sizes not sure what you mean,you must go down on your jetting when installing a daj and then tune with the dial for the best power ,its an on demand fuel system witch means when the bike needs more fuel it gives it to it,