check air bleed valve on side or carburetor,,,it behind a plate with two screws,,,clean and or replace also the vents brass tubes in the bowls may be pluged and also the rubber hoses conected to bottomcheck flow by opening the drain valves siting (on center stand)then vacunm test the fuel flow switch that draws vacumn off carbs to open the fuel to the carbs always remember to shut off fuel at tank,after shut down,,,happy ridding,,, mike