Thanks Goat Herder, but was thinking more about the difference in flow between the stock valve, to a 'proper' valve. If there's a big difference in flow, maybe I may need a change.
But from that post you quoted on 2 Door, I'm guessing the basic flow is 'apparently' enough to run the engine, and if that is the case, I think it may very well be the vibrations on the bike - which means at the end of the day, change the valve for more fuel flow.
My guess is, we may not be able to feel the vibrations, but maybe even the smallest of constant vibrations eventually shake up the fuel, which as you say, temporary loss of fuel being supplied to the engine. Unless you slow down a bit to ease the vibrations, the fuel just keeps rumbling up.
Kind of like a bowl of sand or grain, and you constantly hit a side, the contents move towards that side, or away, forgot which it goes - Whatever the smallest of vibrations is doing, it's moving the fuel up.
Having a bigger flow may add weight to keep the fuel pushed down and running, but then by this theory, if you had really bad vibrations, even a larger flow wouldn't solve the issue since there would be enough shaking to shake up the fuel, upwards.
So I'm guessing two things come from this, eliminate as much vibrations as you possibly can, and use a valve with better flow.
That's just my 2 cents thrown in.