Check stuff...
develop a technique to check each system, then go through the bike one system at a time.
Intake air leak - start the bike and spray around the intake manifold with carb cleaner (did it effect the engine?)
Spark plugs- change them to new (They're cheap)
Timing - get out the strobe
Add a dedicated ground from the engine to the frame or battery (isolastics can insulate the engine somewhat)
Float sticking- pump the bleeder when the engine starts to break up. (did it help?)
Try all the simple tests that you can do without disassembly first. Then you might be moving on to pulling the carb bowls, then jets, then checking the carb body's needle clip's position and placement. You'll find the problem, just be patient and focus on each aspect and keep moving through each one methodically testing as you go.