I ran the bike out of gas Tuesday night, but I had enough in reserve to get me tomy usual station. I filled up, then rode about 100 milestoday and had to fill up at a different station. I then rode another 10 miles before it started sputtering in 4th gear @ about 60mph. I suspect bad fuel or a dirty fuel filter, but haven't had time to look at it yet. Any other ideas? I run 91 octane always, but I suppose that I have to rely on actual 91 coming from the pump.

 

My guess would be water/dirt in the gas. I would suck a quart off the bottom of the tank to check, or replace the tankful ofgas. I have had gas contaminated with diesel causing missing. If it just runs rough, itwill likelywork through it with good gas.

Low octane would cause preignition (ping) not missing.

 

Isopropyl Alcohol will eliminate water in the gas. Doesn't take much (2-3 tablespoons) and you'll be running normal. In humid climates it doesn't hurt to do this once in a while for insurance. The water combines with the alcohol and burns with the gas.