Troubleshooting carbs

Have a 79 gs750. The bike ran fine a year ago, but then was put to the side and forgotten about. Started back up on the project and decided to get it running again. Went through the carbs and replaced gaskets and cleaned jets. All the float heights are set right. Well #2 carb leaks a bunch out of the overflow. Got the bike running and it will idle. I can rev it up, but its "slow" to rev up, and will backfire quite a bit. I pulled the head and went through it, so i'm wondering if maybe the cams are a tooth off or something. I also checked the plugs and #2 plug is black while all others are pretty clean. Any thoughts on it?

Sounds like one is just loading up, first off. Fix that overflowing carb. Sometimes a few good taps with the handle of a screw driver will knock the float loose.

Could be something in the float seat. I rinse them easily by draining the carb bowl, then turning the fuel on while lightly tapping one of the end carbs so the float doesn't stick as well.

Good news is that the bowls are easy to remove without taking the whole carb rack off.