You need to verify that the different elemnts of your carb are working. Are you getting gas from the petcock? Is you float bowl filling with gas? Is the float set at the correct level? The pin should in the middle of the float with equal amount above and below, i think. Is your jet and diffuser clear of debris? Is your idle circuit clear? Most of the gas goes through this hole, so it's important that it's clear. Are all of the access holes closed with little screws?