Before you pull the carbs, make sure fuel is flowing to them. Loosen the drain screws at the side of float bowls to see if fuel pours out.
If not, check back from the carb through the hidden filter to the petcock for obstructions.
If there is fuel, pull the bowls to check to see if they are gummed up. You could spray the various jets with a varnish remover or add Seafoam to the fuel to break down the varnish.
One last thing, do you have spark at the plugs?
