Your bike needs some loving.
Clean and flush your fuel tank, maybe change the fuel lines. Go through the carbs as suggested by Disston. Fuel supply seems to me the MOST likely suspect to me.
I would also check the resistance of your caps and wires as well as inspect the coils and connections. Wirewrkr has good deals on caps and wires. Points should be inspected and replaced if badly worn, then adjusted and timed to perfection. No place to be impatient!
All of this is assuming your heads are torqued and valves are adjusted to spec. Then dial in your mixture and carb balance.
Never underestimate the laxative properties of motorcycling.