Are you using a FRESH NEW GALLON OF FUEL?
Did you replace the fuel tubing inside the tank?
Do you have the carb connected to the correct line out of the tank (feed line, not the pressure line?

If so, and the engine has good compression and no loose bolts on head or backplate then it can only your needle setting.

If you can get your engine running for even a bit, immediately go to the fuel line and squeeze and release it in rapid succession while hearing what occurs to your engine (leave glow on). By manually controlling fuel flow you can determine if your needle settings are too rich.