Motorcycle Repair: 1985 VT1100 shadow, coils, roommate

Question
My roommate just inherited an 1100 shadow.  After getting the engine warm if you shut the bike down it has to cool to start back up.  Also if you ride long enough it will eventually shut down.  When it cools enough (10 15 minutes) she will fire right up like a charm.  The best we can tell when it is warm and will not start there is no fire on the plugs.  We were thinking coil maybe but seems strange that it would be both.  Just looking for some direction.  Thanks for your time.

Answer
You first guess is a pretty good one at least that's where I'd start looking.  Sounds like when it get hot, something opens up and breaks the circuit.  It could be the coil or it could be the ignition modules.  The ignition modules don't produce much heat so I'd start with the coils.


Regards
Rich