I pulled my bike out last night after having not ridden it in a few (3-4) weeks. It started fine on the choke. It seemed to be idling fine. As I got going down the first major street it started feeling a little funny. I couldn't tell what it was at first. It felt a little bit like if you leave the choke on too long. I made sure the choke was all the way off and still felt the surging a little.

I opened it up to get on the freeway and it nearly wheelied on me in second (with my wife on the back too). We cruised onto the freeway and all seemed fine until the surging got worse and worse and worse until the bike died!

We coasted through an interchange onto a different freeway when somebody else on a bike stopped to see if they could help. He took my wife home to get a truck. I was left with the bike and tried coasting a ways.

I tried a few more times to start the bike and finally got it to fire with the choke on. I opened it up to nearly 100mph and got almost to the first available exit ~2 miles away when it died again and I was coasting. I couldn't fire it back up from there. I had to wait on the side of an off-ramp to my wife to get back with the truck.

What could have caused such a condition? The tank was drained and carbs cleaned since a few months ago when I did have some bad gas develop in there over the summer. The tank was full the last time we rode and we have only done ~30 miles on that tank so far. The gas doesn't even smell bad. Why would it surge, sputter and die like that, but come back to life with the choke on?

I'm going to clean out the carbs and probably change the fuel again. If there's anything else I can/should check I'm all ears.

 

Going by your avatar, is yours the carbo-chicken bike with a CF tank? If so, does that tank have a different or alternative venting system? Sounds like a vacuum lock problem: bike runs fine then starves for fuel, wait a bit and it runs again.