try a new spark plug.
even thos it only has 7-10 hours on it, they aren't all perfect.
it coudl also be a bad spark plug wire, a bad cdi box or a bad magneto.
do you have anything hooked to the whote wire coming from the engine?
if so, disconnect it and do not hook anything to the white wire and see what happens.
hooking somethign to the white wire (such as a headlight) will draw too much from the magneto, making the engine lose spark.