Two things you are missing. One, you said that the screw on the bottom of the carb is fully tight. Bad
This screw controls the fuel going through the carb. Open this screw one and one half turns from lightly seated. this will allow gas to enter the air horn and engine. Two, try taking off the ground wiring on the ignition magneto. This wire could be shorting, which will give you a NO SPARK condition. This wire is the kill switch wire and if you have it grounded the engine will never start.
This screw controls the fuel going through the carb. Open this screw one and one half turns from lightly seated. this will allow gas to enter the air horn and engine. Two, try taking off the ground wiring on the ignition magneto. This wire could be shorting, which will give you a NO SPARK condition. This wire is the kill switch wire and if you have it grounded the engine will never start.