Do you have a fuel filter on this beast ? On the other hand it may be vapor lock, in effect the fuel is boiling in the carb after you shut it down. Acts the same as if it's flooded when you go to start it. Try it again, but this time after you shut it down, wait the 4 minutes or so, then pull the aircleaner assembly off the carb and before trying to start it, work the throttle a few times while looking into the throttle bores to see if the accellerator pump is shooting fuel in. If not then thats a sure bet it's vapor locked. You're trying to crank it, mistakenly thinking it's flooded, but in reality, you have to crank it until the fuel pump fills the carb bowl back up before it'll start.