Air/Fuel Ratio Adjusting procedure

Step 1: Air adjusting screw

Turn adjusting screw all the way in then back off
¾ to 1¼ turn on 50cc engine
1 to 1½ turns on 90cc engine.
 

Step 2: Adjust idle RPM. (Warm Engine)

Turn the adjustment screw in or out to adjust the engine idle speed to
Between 1700—1900 RPM.