I just got a 2000 drz400. It sat for 3-4 years before I got it and it had clogged jets. I rebuilt the carb and it ran cherry. Then, one day I was leaving work and it started backfiring flames and wouldn't work. Since then I've not been able to start it. The bike just whines, but won't catch. I put a new plug in and noticed this morning that it barely smelled like gas. I know it's a fuel problem. Any thoughts??