Stator replacement, '84 1100 GPZ

I just replaced the stator on my '84 1100GPZ with an after market unit of claimed higher output (windings of thicker wire gauge). The original unit was fried, at least 4 of the armature sections. I was only getting maybe 11 or 12 volts charging at 4000rpm instead of 14.
My question is, what makes these things burn up like that? I'd hate to see it happen again. So far, so good.
I haven't detected any shorts or frayed wires. What's the common ailment?
Thanks,
Stephen

If it burned up then it was shorted out somewhere, may have been an internal short in the stator windings.