The dangerous situation is if the engine kicks back instead of firing in the forward direction. This locks the crank tight into the lugs, and usually breaks a wrist, or worse! To minimize the risk, always place your thumb under the crank, alongside your fingers, instead of getting a death grip on the handle. then, pull the crank up sharply 1/2 turn. DON'T push down on it!
The Model T and Model A Fords with the manual spark advance were the arm-breakers, as people would forget to retard the spark before cranking the engine! Ditto on the old Harley-Davidson bikes with the spark advance on the left handgrip, but they would launch a rider over the handlebars when he kicked the starter lever!
Jerry
