Hey, Tom, I believe that's a Fuel adjustment screw, not an air screw? 2 strokes use an air mixture screw but 4 strokes a fuel mixture screw.

Reason I correct that is because it can confuse the adjustment, if one thinks opening it will cause more air, and a leaner mixture. Just the opposite, that opening CCW will cause a richer mixture?

I've just been fighting with a real mean & ugly little 110 carb and had trouble finding out that it's a fuel screw, which messed up all my good intentions with adjustment!