What color is the spark plug? The engine must be completely cool to the touch before removing the spark plug or you risk damaging the threads in the cylinder head. If it is black, try raising the clip on the slide needle 1 position. This allows the needle to drop down further and reduces the amount of fuel added to the incoming air (leaning the state of tune). Note that this only affects the tune from 1/8 throttle to 3/4 throttle. If this helps, ride it for a while and check the color of the spark plug again. You are wanting a chocolate to leather brown color.
If you are having problems at throttle positions above 3/4 throttle then you need to re-jet the carburetor.