Hi joabthebugman,
Even if the fuel shutoff is defective the carburetor should not drip gasoline. This means you have carburetor issues for sure. The most common problem is the small passages in the carburetor are stopped up. I suggest adding 4 ounces of Gummout carburetor]fuel injection cleaner to approx 1/2 tank of gas. I know the bottle indicates a lot less, just add it as I suggest.
Sadly there were a lot of carburetors sold to fit the Whizzer motor, and about 95% were not correct to the motor. The bogus carburetors often can't be adapted to the motor without major expense [wrong cut in slide, wrong needle taper & length, wrong pilot jet, wrong main jet, etc,].
Please send information from the right side of the carburetor housing to aid in identifying the unit [IE Ken Tse, Kie Han, etc.]. You also need to measure the mouth of the carburetor to determine size, IE... 22MM, 26MM, 19MM, or 17.9MM.
The correct original carburetor normally sells for over $110, whereas the fakes are normally under $60.00.
If it is the correct carburetor the main jet WON'T be marked and can be either a 98, 90. Some of the later Whizzer units had an 88 main jet and some were marked [not many].
If the motor is upgraded the normal main jet should be either a 84, 85, or 86 main jet, the 88 or larger is always too rich. If the motor is basically a stock NE the main jet should be as little as an 80.
You can resize the main jet, however replacements are still available if needed.
As Jim mentioned, you should check the camshaft setting [one tooth advanced], and also check for lifter wear [if not equiped with mushroom lifters] and make sure the clearance is set correctly. Factory clearance settings are .009" on both lifters. On modified motors the setting should be .006" intake and .008" on the exhaust.
Have fun,