I'm bored with 750 models assembly issues so learning 850ES stuff to convince me not to try. I'm pretty sure that with a proper taper fit a key way is just for initial alignment, even on the torque scale a Commando applies through it, If not then I'd expect to find more blacksmith welding of key to crank slot. I have found welded in keys on Combats and lawn mowers, but their fit was not that good.
I may try a key-less experiment, as nothing much should happen if it should slip, any more that with clutch slippage, as long as nipped up right for initial ignition timing.
If it fails to hold damn hi power loaded I'll eat my key way, if it don't slip - will someone here eat their words mis-quoting hobot message?