Fuel filter in, flushed float bowl, etc.
Finally got to ride this weekend, and, same deal. It thinks it's a racehorse and pi$%es like one. Took off the float bowl plug and there was no dirt. Tapped on the carb from many angles and finally it quit flowing and I rode in.
I checked the float level the first time it was ever off, and that was good. Needle valve looked like new at the time, I will check it out more carefully.
If the float was set too high, why would it ever shut off? When it does it, it's not a trickle, it's a solid flow out one of the tubes, sometimes others participate. Maybe looking at which tube it is would yield a clue?
This bike sat for years, so there are lots of possibilities. If the spring plunger in the float valve is sticky, there could be times when the needle is shorter!