Hiya, Ronny!
First, an air leak will make the bike run lean, not rich. If you're rich with an air leak (!) something else is going on. Second, those inlet pipes / stacks / joints are replaceable. Part number is 3HE-14453-00-00, US$15.76 MSRP at any Yamaha stealership, but you can probably pick it up cheaper online.
Of course, "cheaper online" can sometimes be a little meaningless when you start including shipping...
