I found some of the things she told me about the cutting-off issue odd.
I asked how it would die....would it cough and sputter and bog like it ran out of gas? Or was it like someone hot the kill switch and turned off the key?
She said it was like the latter. Just cruising down the road and it would die.
I asked if it would restart and she said "Yes, but I'd have to rev the piss out of it for a while". I asked how soon it would start and she said, just long enough to make me frustrated, sitting by the road!
Now, all of these things point to something electrical, to me. Carb issues don't usually just STOP the bike. I was guessing kill switch or ignition switch...and then I found this when I got it home.
I knew the choke cable was stiff and was showing it to my buddy with the van, when I saw the choke plunger not moving.
Choke on, plunger lifted.
Choke off, plunger still lifted!
I can reach in and push the plunger back down with the tip of my pliers. Now I'm wondering if she wasn't riding around with the choke on and fouling the plugs? That would explain the "revving the piss out of it", to get the fouled plugs clean again.
It's late, and I'll investigate further tomorrow. I don't know if I can access the choke plunger to remove it without pulling the carbs. I'll also pull a couple of spark plugs and see what they look like.
I sure would like for it to be something simple like this instead of chasing electrical gremlins.