Generally, I don't use rebuild kits, I just buy the individual parts needed. Rebuild kits are a waste of money for the most part. You don't need to replace most of the stuff they come with and many times the jets included are the wrong sizes anyway. If someone brings me a rebuild kit with their carbs, I will try any needed parts. If they work, fine, if not I get genuine Mikuni replacements. That would mean either the Yamaha shop or someplace that deals in Sudco parts (the Mikuni distributor).
Before replacing, follow the advice given in prior posts. Carefully clean the float needle seat and carefully check the float level from both sides. Insure the float moves freely on the pivot pin.