Those motors will run on 1 carb but not well. I would remove both carbs and clean them well. What I found with mine was the float needle got stuck in the closed position ... very common if you have original OEM rubber tipped needles. You will need a pair of needle nose pliers to get it unstuck, tapping it won't work. Unfortunately there is nothing that you can do to free the needle in the bottom carb without removing it. The ethanol in the fuel causes it to swell and stick in the seat ... happened to me 3 times!
I am now running an enzyme additive that is supposed to stop that. As a practice, I pull my fuel line with the motor running at the end of an outing and burn some of the fuel out of the bowl. Not run it dry, but enough to allow the float to drop, therefore the needle is not in the seated/closed position.