Running Then, Not Running Issues HELP!!!!

[chopper_mrns]

I looked around for a bit but couldn't find anything.
I have a 78 XS650 Bobber that has been rewired with just a headlight and tail light. No speedo, turn signals ect. It also has points.
I hooked up a smaller 12 volt battery to run the coil for start up.
Here's the problem, the bike starts and runs fine if you go around town or stop light to stop light type riding, but when you go to the freeway and ride at high speeds for more than 30-45 min it will shut off, all lights will be out and bike won't restart until you let it sit for about 10 min. Then it's fine for another 30-45min.

What could it be?
Thanks in advance!
jon®

 

[gggGary]

Smells like the recifier rotor, stator or battery overheating shorting out? You may be boiling that poor little battery. Chunk a larger battery in the system strap it on the seat what ever. See if the problem goes away. What regular are you running?

 

[chopper_mrns]

Hum... Really? Running a newer reg/rec combo from a later xs650. That would explain the round the town working ok, lower revs and higher revs for a short amount of time.
Is there a way to step the voltage down to the battery?

 

[gggGary]

Did you un-ground the inner brush and switch to nylon screws? If not, that would explain everything. You in effect have no regulator, full charge full time. If so I am surprised an ignition coil hasn't cried uncle and gone home for good

 

[chopper_mrns]

The inner brush is un grounded, but which switch? As for the coils, I noticed that when the bike is just switched on not run, the left coil will begin to heat up... Bad?

 

[gggGary]

No a coil will heat on a points bike that isn't running, one set of points is usually closed so one coil will heat and eventually (some times eventually isn't very long) it will burn out. The two top screws (holding the inner brush) have to be nylon, if they are metal they ground the brush.

 

[chopper_mrns]

Ok, good on the coil.
The two top screws are nylon on the brushes. I'm gonna test the voltage to the battery while it's running and report back.