Suzuki C90 Engine problem
 

I have a Suzuki Boulevard C90 which has a very annoying problem. The rotor for the speed pickup that rides on the right-side of the output shaft comes loose and winds itself into clutch gear, which partially covers it.

I see that the end of the shaft is slightly below flush with the inner ring of the bearing, which seems strange since this places an axial load on the bearing when the rotor is tightened into the shaft end. By trying to close the gap it tries to pull the shaft further through the bearing. Only a few thou, but the shaft is definitely shorter than the outer face of the bearing.

I've loctited the rotor into the shaft thread but it eventually still unwinds. Maybe I need a shim on the end of the shaft so the rotor tightens onto the face of the shaft end rather than pull against the bearing?

The parts book from Suzuki is so bad it doesn't even show the existence of this rotor.

Anybody seen this before?