Actually. There is a pin about 3/8 diameter by about 2 inches long going through the starting crank on the end opposite the handle, as well as a cotter key, spring, plus retainer for the spring. The pin in the starting crank engages two sharp dropoffs in the pulley when you push in and turn the starting crank. When the engine starts two ramps behind the dropoffs kick the starting crank out of the pulley.
I have had to replace the pin on my WC. The previous pin, probably a replacement, was made of very soft steel. I used a case hardened pin from the hardware store and tack welded it in place.
Dan could be correct about the bolt in the pulley being loose. The only thing holding the pulley to the crankshaft is a bolt with lock nut seated into a depression (shallow hole) in the crankshaft.