The hub taper on these motors is slightly different from the taper on the crank making them tighter at the bottom. These also require a higher torque on the flywheel nut. This causes the flywheel hub to stretch to fit the crank taper and gives a REALLY tight fit so there is no load on the woodruff key. On the other models, the key helps keep the flywheel in place. On the small key models, the hub does this job. That these flywheels are Hell to get off attests to the fact that the system works. . . 😆
