A stable idle speed is important to prevent engine from turning off.
Check this to know How to Adjust Idle Speed for SXY MOTO Holeshot Mini Dirt Bike:
Locate idle adjustment screw located on the carburetor, below the transmission
If the idle speed is too slow, the engine will fail once it starts.
Rotate the screw clockwise 90 degrees.
If the idle speed is too fast, the bike will move even you have not rotate the throttle.
Rotate the screw counter clockwise 90 degrees.