In order to adjust the carburetor it is necessary to warm the motor up first. The motor should have at least 5 minutes running time before any adjustments are made.
On the left side of the carburetor near the front is the idle mixture screw.
On the HuaSheng motor the idle mixture screw is a fuel adjustment, not an air adjustment.
Simply adjust the screw for maximum idle, and then turn the screw approx 1/16″ counter-clockwise [slightly rich].
Check the throttle response, and adjust the mixture if there is a hesitation. Turn screw clockwise if it “bulks” and then catches on [rich], or adjust screw counter-clockwise if it accelerates and then drops off quickly [lean].
Quenton “Lee” Guenther