Needle problem?

[Guest]

This is another one of those "It was running fine but then" deals. Haven't had any issues with her this year, but last night while running around 4000rpm, it would fumble when I gave it gas. I don't get it. I shouldn't have to mess with this bike that often, should I?

[Dave8338]

I know, it will sound like a broke record, but have you done the intake o-rings?

[crapwacker]

EVERYTHING last year.

[Dave8338]

HMMMMMMMMMMM...sounds lean...just started...check fuel flow from the petcock. Any chance there is a hole in the vac line or are you running a Pingle?

[crapwacker]

It's an aborted attempt at a Pingle.

[Dave8338]

It's an aborted attempt at a Pingle.

That would be my first place to look.
Any inline fuel filter?
How does the inside of the tank look?

[crapwacker]

Clean tank, sintered brass type filter

[Dave8338]

Bypass the filter and see what happens.

[crapwacker]

I'll try that, thanks. I'm currently looking for a factory petcock. . .

[Dave8338]

I'll try that, thanks. I'm currently looking for a factory petcock. . .

I went the rebuild route the first time and had NO luck. Maybe I'm just not good at fixing things.

I strongly suggest the new petcock for $50+ Money VERY WELL spent.

[crapwacker]

well I removed my inline filter but still have a fumble at 4000rpm. I can be running steady at that rpm, but when I give it throttle, it'll stumble a bit, but will come out of it. It will run well after that, but any increase in throttle will make it stumble. Above say 5500rpm, I don't have the issue. Coincidence or not, this started happening after I installed relays. I replaced all orings and completely rebuilt carbs last season. Airbox is sealed, and valves are 1500 miles away from being checked.

[Turtleface]

well I removed my inline filter but still have a fumble at 4000rpm. I can be running steady at that rpm, but when I give it throttle, it'll stumble a bit, but will come out of it. It will run well after that, but any increase in throttle will make it stumble. Above say 5500rpm, I don't have the issue. Coincidence or not, this started happening after I installed relays. I replaced all orings and completely rebuilt carbs last season. Airbox is sealed, and valves are 1500 miles away from being checked.

Which relays did you install? I'd check that first thing, make sure all the connections are good.

[crapwacker]

found a vent line had come off #4 carb. Haven't gotten to test yet, but it makes some sense. I only have the issue in top gear, so wind turbulence at that speed must be just right to affect it. We'll see