So I went riding yesterday and when I went to start my bike to head home the battery was dead. Immediately I knew there was somthing up with the charging system because the battery is brand new.. Did some testing turns out the stator isnt producing any power. So I pull the primary to replace it and I find this... The stator rotor is broken right in the center at the splines, the center broke out in almost a perfect circle right along where im assuming it was welded. Has anyone seen this before ? I did replace the compensator sprocket recently but idk if that would have anything to do with this. Any advice as to what could have caused this would be greatly appreciated.

Bike is a 1993 dyna

 

you're not the first this has happen to !!! do you know how many times the crank end nut has been taken off and back on ??? with a torque wrench or air racket ??...we think this is a fatigue problem possibly from the nut first being over tighten and then coming loose just a bit (from heat cycles) ...and rocking back and forth (when on and off the throttle) ... be sure to check the crank shaft splines too !!!
all the torque is put on the washer (spacer) that's on the inside...in that one area...every time it's pull up tight ...the metal is stretched in the same spot every time ....
check ebay ...get a new rotor and stator , and we always change the voltage regulator too ...
good luck ...

 

Ive taken it off twice since Ive owned the bike, but I used an electric impact so I feel like the force definatley wasnt as abrupt as an air impact.. Thank god the crank splines look good. Thanks for the info... Makes sense

 

I torqued it back to spec with a torque wrench both times

 

Common problem.. It's not torquing that messes it up.. It's support from the spacers that the rotor sits between.. Some like to machine the inner spacer so that it has a flange to support the rotor and use wider spacers between the compensator and the rotor..

You can also buy a rotor with a heavier boss.. IIRC Spyke makes them and they are available through Drag Specialties.