once again, the clip position on the jet needle does nothing at w.o.t. it only affects the mixture from idle to about 3/4 throttle.
these engines do not have reed valves (as nwohater mentions).
a stuck float will not cause 4 stroking, a stuck float will result in either A. the engine will not get any gas and will not run, or B. the carb will flood over and spill fuel all over the place.
first thing i would do is make sure that the choke isn;t partially closed. the choke on an n.t. carb is very simple and they can vibrate loose. If you have a cns carb, the choke is more like an air bleed and you will have to make sure that it's closing all the way when you turn the choke off.
then, i would pull the float bowl off and look at the main jet. the main jets on these carbs have been known to vibrate loose and fall out into the float bowl.
check your air filter, make sure it's not plugged up.
if your engine is 4 stroking you are not getting enough air....like the choke is closed, air filter plugged or the jetting is too rich (too much fuel, not enough air).
i have found that 80% of getting these engines to run right is in the tuning of the carb (re-jetting). also, a better exhaust will help you out too, like an expasion chamber, the stock mufflers plain suck, and they will plug up over time.