Ahh, injected in 2002... learned something new today! Thanks Buelly
I don't know much about the tubers
specifically, but I do know the basics, and I can diagnose anything
. Do what Lunatic said. Those are the starting steps to proper diagnosis. If you just jump around asking broad questions and throw parts at it, even getting lucky won't teach you how to fix the next inevitable problem.
Didn't we go over this before?
Do you actually have a problem? You didn't mention it running poorly, or starting poorly? This is an old bike with a early gen FI system, not a car with a catalytic convertor, It may just smell like that
especially with a 'Race map' in the ECM.
You did say you smell gas BUT over rich running and raw fuel leaking/venting smell completely different. Is the pipe really sooty?
A slightly black plug is ok. An O2 sensor in only the rear exhaust header is the same as the XB's.