Well, I'm nearly at wits end. I took the bowls and floats off again, carbs still on the bike, and just pushed the valves up with my hand.
The fuel flow stopped
/
Put everything back together, and it's doing the same damn thing as before. Too much gas, bogs down, and eventually dies unless I regulate the petcock manually. It looks like only the left one is doing it as well, but I can't tell exactly where the gas is coming out of, so I can't be sure.