I've owned the bike for almost 7 years. I haven't had any issues with the way it ran until recently. It started by doing some backfiring out of the carb and then the exhaust got it where it's just backfiring out the exhaust now. It starts easy and idles beautiful. But when I get the RPM up is when it starts backfiring. It will only start backfiring when I'm rolling after I let off on the RPM to just cruise. The only thing I haven't checked is the timin