This is probably a stupid question with an easy fix but here's my problem. I've had a '99 XR400 I bought used about 6 months ago. The thing runs great, I've had no problems with it. I sold it to my brother today and am going to go bike shopping. Anyway, we go out to start it up and I turn on the gas and I have gas leaking out of a tube at the bottom of the bike . The tube goes into the bottom of the carb and it is like the gas is just running right through it . I've done oil changes and simple stuff but that's about it. Can somebody tell me what's going on and is this an easy fix? Thanks in advance for any help on this!