Set the screw by sound if it's adjustable. With the bike idling turn it slowly until you find the point at which the bike's idle speed is the highest, leave the screw at that setting and then adjust your idle down to where it should be. It will purr like a kitten. Only caveat is if it's too lean from factory you would have to turn the pilot screw so far out it practically falls out, in which case the jet needle adjustment is the way to go. Most bikes are happy around 2 1/4 to 3 1/2 turns out on the screw with a factory carb. I would definitely recommend the Mikuni carb like you're looking at though, definitely the way to go.