Starter slipping on crank on KZ1000 1982

Hi,
I recently had a problem getting the starter turning the engine over. It sounded it was just spinning. Taking the cover off revealed that the larger bolt on the crank was not holding the rotor on the shaft. The big problem is that the cone shaped end of the shaft has worn and so has the rotor. Any suggestions for a fix?

I think there are a few options. Depending on the wear, if the rotor is badly worn, it can be replaced, if the crank end is badly worn it also can be replaced but is a big job.
If they are not to bad, you can Lap the two together with some Valve lapping compound. Then once the fit checks good with some Bluing compound, clean it and use some Loc-tite bearing retainer, and torque it up.