I removed my tank to get to the top of the carb. Screw the top of the carb off by hand, then you can remove the cable, and the slide. Under the slide sits the needle, take it out, there is a clip on the needle that you can move up or down on 5 or 6 notches. If the clip is on the bottom notch, it is raised to the maximum, allowing more gas to pass by it. If the clip is at the top notch on the needle, it is at its lowest position, allowing less gas to pass by it.
This may seem confusing, but when you have the top of the carb off, it will become painfully obvious how it works.