PUll the air box cover off or cut the last 1.5" off the end of it so you still have all 4 clips, try a 320 mains, stock pilot, and try different needle positions. Once you find the best needle position, run it wde open throttle in 6th gear for 5-10 seconds, shut it down , coast to a stop and pull the plugs, take a pic of them or put new ones in and keep the old plugs. Post a pic on here. We can tell you if your rich or lean on the mains by looking at the plugs, and can explain better why. Also take note of how well it starts cold and warm and whether you need the choke or not, this will help us determine your pilot jets. Now you have some homework to do.