1. The first step is to identify where the engine is not performing well, bearing in mind that the carburetor's performance is determined by throttle position, not engine speed.If the engine has a problem in the low speed range (idling to 1/4 throttle opening), it may be a failure of the fuel saving valve or plunger.If there is a problem between 1/4 and 3/4 throttle opening, it may be a fault of the oil needle and the main nozzle;If there is a problem between 3/4 and full throttle, it may be the fault of the main port.
2. After determining the throttle opening at which the fault occurs, start adjusting the carburetor.Screw the idle speed adjustment limit screw to the engine speed of 1500rpm/min-2000rpm/min, and slowly unscrew the mixture adjustment screw to the left and right, until the engine speed runs smoothly. Then adjust the idle speed screw to make the engine speed to 1000rpm/min-1300rpm/min.