HELP! I have a used 1300R, stock pipes, air, etc, no engine mods. It's been running great since I got it, about 4k miles on it. Suddenly, today on the way home.. it started going crazy! On acceleration it would start sputtering, lurching, and flailing all over the place.. and if I try to push past it.. it backfires. It feels like it's just about to run out of gas or something.. but it's a full tank. Once I got it up to speed, I was able to cruise along at 70-80mph with no issues.. an occasional minor stutter, but nothing major. Idle sounds perfectly normal. Rev the engine sounds ok. But when I engage the clutch and accelerate, it starts going haywire! Once I can get it up to speed, things calm down... but getting there is tough. I thought maybe bad gas... but i had gone through 100 miles of that tank before it had any problems. If it were bad gas, I would have felt it right away.
Any ideas what could be causing this problem? Help!?!