750 alternator rotor goes awol

My GPz750r1 rotor slipped off the crank recently, fortunately it was on a cold start and I managed to fix it. I guess it may have been slipping for some of the 50 miles I did the day before.

The bolt had come out and the rotor had damaged the stator, although still getting 0.9 ohms between the yellows and infinity between yellow to ground. The rectifier might be damaged as it is jumping around all over the places from 11 to 19 volts using a digi meter.

I ground the crank nose with grinding past, solvent cleaned and tightened up the threadlocked bolt with an air ratchet. I don't think it has been removed before so maybe 33 years later it just worked loose. In future I'll check these rotor bolts for tightness.

You could have suffered some serious damage.

How do the magnets look?

Strange how the R/R seems to be affected because of this.

The rotor flopping around, the magnets could have been causing a fluctuation in the fields and burning out some diodes. I think that's what happened to my R/R.
Steve

The rotor and magnets look fine, it seems there is very little room for the rotor to flap around inside the casing. I never checked it for tightness as my experience of these is they are stuck tight to the crank taper, even when the bolt is removed.

Although the windings have had a bash, the winding resistance and insulation to ground is checking out about right.

On the suspect RR unit, I double checked my charging voltage but with an analougue meter this time, it all checked out ok and the needle moved nicely to the right as the rpms increased.

it seems some RFI noise was affecting the digi voltmeter. It was jumping all over the place even when disconnected from the battery whenever the engine was running.
I'd recently dumped the resistor caps and changed the HT wires for 7mm copper, I'm not sure if they are resistor plugs fitted.

So it seems all ok again now. Just as well it didn't happen on a long run, by the time the battery would have flattened it is likely my crank nose taper might be badly damaged.

I think probably worth checking these for tightness in future.