AVS or AFB being a 600 i would guess AVS.
go out and turn you air fuel mixture screws all the way in(counting the turns) and then back out to where they were. the screws in the front of the carb. count the turns on both the left and right side.
Now turn your idle screw in until it just comes off of its seat. count how many turns it took and then return it back to where you had it.
Let me know how many turn of all three screws.
