Symptom: bike surging; Diagnosis: ??

[yeagermeister]

After riding about fifty miles today my bike started surging.  I was doing about 60 mph, at 6000 rpms most of the way - just taking it easy.

It was like when you're running out of gas - erratic loss of power, and bad throttle response.  So, I pulled over and checked the gas, had a full tank still.  Then I rode another couple miles and the problem went away.  After lunch, it was fine for the 50 miles going back home.

Was I overheating, or was it a carb problem, or what?   :dunno:  Buddy says it might have been water in my gas tank.

Any ideas?  

[manofthefield]

Did the problem fix itself right after you stopped and opened the gas tank?

[JCH]

That's similar to what mine is doing, except mine surges and croakes.   If its not a vacuum problem like manofthefield said it may be the bike running lean.  Srinath could probbaly speak to this.

[yeagermeister]

Did the problem fix itself right after you stopped and opened the gas tank?

No.  I closed it, then rode for half a mile or so, and it went away.

[treybrad]

I was riding 2 up the other day, had ridden about 35mi w/o any probs then all of a sudden it started surging/dying on me. I switched to PRI real quick thinking it was either the fuel starvation thing our bikes sometimes do or I was running low on gas. Changed to RES after a couple seconds and rode until I had a chance to see how much gas I had... I was going pretty fast those first 35mi; probably about 75-80mph with a passenger and my 15t front sprocket, the RPMs were around 8-9k.

It looked full, but looks are decieving sometimes looking in that tank so I filled it up and sure enough, only held 2 gallons, so I had plenty of gas. It would keep doing it too, even with a full tank. Sometimes it wouldn't do it for a few miles, then it would start doing it.. pretty annoying. Should I check my petcock? Is this the notorious "highway fuel starvation" thing? It'd never happened to me before.

Dropped off my passenger and sat around for a few minutes before going home. Hopped on and it never gave me any problems the rest of the day, and I rode another 70mi or so...

Anyway, not trying to post-jack, sounds like we had the same problem.. almost the same scenario.

trey

*edit* oh yeah, at one point, after I got gas, I popped the tank again to make sure the cap was seated right, checked all my lines going to/from the carb (including the vacuum line) and everything looked good. Weird thing was, I have an inline filter that I can see in and the fuel level still wasn't as high as usual. I would turn it to PRI, open the tank and the filter still wouldn't fill up to the usual level... so for some reason the gas just wasn't flowing into the lines.. any clues? After I got home after riding another ~70mi w/o problems it was back up to the level it's usually at... I even pulled the plugs later that day and they looked perfect.. so I know the 2nd half of the day she was running well.