If it was me I would probably pull the gas tank and clean it out. Check the fuel line for cracks and replace the inline filter.. Next I would Pull the gas line off at the carb. (have catch can to catch any gas ruining out the line) see if your getting gas to the carb. If gravity feed (tank higher than the engine and no fuel pump) gas should free flow. IF you have fuel pump still pull gas line off at the carb. crank the engine over with the starter and see if fuel squirts out. Now that you know you got fuel to the carb. then it's got to be in the carb that's not allowing fuel flow.

I usually test carb. when off by connecting hose to the carb and blowing through it the flip it up side down and see if the needle seats and seals the air off. This at least let you know that fuel should flow through the carb. One last thing if you have fuel pump and it weak or won't pump check the vacuum hose that goes to the head If the hose is cracked it will suck air.