Instructions
How to Adjust Idle Speed for MT Series 40cc 4-stroke Dirt Bikes？
This is the engine
and this is the carburetor
This is the idle adjustment screw
Rotate the screw clockwise 90 degrees
the engine idle speed will increase
If the idle speed is too slow, the engine will fail once it starts;
If the bike's idle speed is too fast, the bike will move even if you have not rotate the throttle.
Rotate the screw counter-clockwise 90 degrees
the engine idle speed willdecrease