Float level double check

[Charlie-brm]

That's where I am with fuel level on the two outer bowls I checked in place on the bike with a tube.
It's level with the point where the screw head meets the bowl casting. I measured that at 5 mm down from the seam between the bowl and carb body.

The reason I am posting is I've got lagging, lurching, bucking, etc. when I'm at low throttle, especially once it's warmed up.
eg. residential stop and go traffic, coasting down to an intersection, it's really rough. When I roll it on for higher speeds there is a brief delay then it surges on acceleration I'm off and can pull continuously over 50 mph. It's fine at higher speeds. And again when I'm stopped at idle it's fine.

The carbs just had a total cleaning ( 3 times min. checking passages) and new o-rings in the mixture screws and float valve seats. The screws have been turned back out 2 1/2 turns. Certainly I think it requires a tuning now ( I have access to a synch tool) but I can do that without pulling the carbs for the umpteenth time if this level seems OK to most observers.

[racerrad8]

1st thing...

Did you jack up the front of the bike to level the carbs before taking that measurement?

If not, you need to jack up the front of the bike to bring the carbs level, then check the height.

The Yamaha spec at level is 3.0 +/- 1.0mm

Randy

[Charlie-brm]

Leveled the bike so the carb bowls are level front to back, side to side. Got just over 5 mm again from the fluid to the seam. One carb was worse - almost 7 mm.
Pulled the bowls off and put the carbs up on edge so the floats just flop against the valve without exerting weight. 21 mm to the top of the round part of the floats, 23 mm to the flat and square top of the float.

I would have thought at 21 mm the level would be at spec or higher, not lower as I am witnessing with the plastic tubes sighted against the mounted carbs. So now I am confused and holding off for a revelation. Me, I'd do what it takes to make the in place levels right but that could mean pushing the floats several mm off spec.

[Charlie-brm]

Last night I bent the float tabs in an attempt to get a higher fuel level but even a 2mm change had the floats hard against the carb body. As I was expecting, then they were not able to seal the needles so it immediately spilled gas as fast as I could top it up. The floats are going back to their previous setting.

Back to square one and my initial problem - lurching engine at low speeds off idle. What's next?

[movenon]

Did you ever get your carbs synced ? And fuel / air adjusted ?
INMO if the float levels are close to factory spec's you are OK. Mine are a shade lower than spec and they are just fine for normal riding.
George

[racerrad8]

Last night I bent the float tabs in an attempt to get a higher fuel level but even a 2mm change had the floats hard against the carb body. As I was expecting, then they were not able to seal the needles so it immediately spilled gas as fast as I could top it up. The floats are going back to their previous setting.

Back to square one and my initial problem - lurching engine at low speeds off idle. What's next?

Something is not right... The float should not be anywhere touching the body at 22mm.

Something is wrong.

Randy - RPM