I just picked up a 04 WR450 today that has been sitting for a few years.. The carb is leaking gas out of the drain hose at the bottom of the bowl. The drain screw doesnt go in all the way.. Is it supposed to? its about an eighth of an inch from going all the way in.. any ideas as to why? If i shut the gas off, it wont leak, the second i turn the gas on it leaks like a sieve..