A hotter plug will reduce carbon formation on the insulator of the plug. Your problem does not sound like a plug problem but a carb problem. If it were my bike, I would take the carbs off, clean them carefully, set the needle height to stock, check jet sizes to be sure they are stock and set the float levels and static sync the carbs so they all open together. I have found that it is best to set the float levels and then test them prior to re-installation. I use a modified drain screw which has been drilled through and a nipple soldered to the end. A small hose is attached to the nipple and raised up so it can be used as a sight glass to see the actual fuel level. Fine adjustment of the float tang is then done to set all levels within a mm of each other. I set mine to 3 mm below the bowl flange. Once complete, reinstall the carbs, set the air screws to stock and see how it runs. Your work may not yet be done. If you are running pods or have made other modifications it may be necessary for jet and needle adjustment as well. This is all documented on the forum.
Good luck
