The larger the # on the jet, the more fuel it passes and the richer the mix is to the motor. You'll want to reduce your jet size in order to lean it out. But wait...
The main jet is used during throttle positions of 3/4 to full throttle. Don't confuse that with speed. Speed is not part of the equation of jetting, throttle position is. So, if your plug is black AND you are riding mostly at 3/4 to full throttle, then the main jet could be adjusted to a smaller size. However, if you normally run your throttle at 3/4 or LESS, then leave the main jet alone and adjust the needle. The needle has 5 positions to put the clip. As the clip on the needle is moved UP, the effective length of the needle is longer and is shoved further down into the emulsion tube (AKA needle jet) and leans out the bike. Most needles are on the center of the 5 possible positions with the clip. Move the clip UP 1 position and give that a try by installing a new plug and riding around for a good amount of time to get a read on the plug. If it's still black, try moving the clip up one more position. Moving the clip is much easier than changing out the main jet. All you need to do is unscrew the top of the carb and pull the slide out. The needle is in the middle of the slide. Pull the spring back, unhook the throttle cable, and push the needle out for adjusting the clip position.
Good LUCK!!

Last Edited By: skipro3 Jan 19 14 4:48 PM. Edited 1 times.