Start the engine , spray a light amount of WD-40 around where the carburetor connects to the intake. If the engine dies or sputters you have an air leak there. Seal it with an oring or some sort of high heat silicone.
Also the spark plug that come with the kits are junk. If you ran 16:1 ratio for break in , I am sure the plug is toasted. Change it if you havent already.