Look down the carb, pump the throttle.. you should hear and see gas squirting out of the jet. If you don't, you got a fuel delivery and or carb problem.
Disconnect the fuel line, dump some gas in the carb, leave the choke wide open, and see what happens.
If it starts and runs till it burns all the gas up, then i'd suspect your problem is fuel delivery or something to do with the carb.
If it still won't start, you have some other problem.. timing? electrical? stuck valve?
