2003 Vulcan 800. Got hot and quit running. Motor is not siezed. No power to the Headlight or Starter. All other lights work fine. Went under the seat looking for fuses and relays, but, to no avail.

Could be a bad battery since the headlight and starter use a lot more current than the other lights.

Not sure about your 800 but V-twins have engine temperature sensors on them and they will cut off the motor if you are overheating the engine. I have had bikes in the past that would pop the main maxi-fuse 40 amp if the motor was overheating and ready to shut off.

I'd start with the battery and checking fuses. Before you spend the money on the battery disconnect it and hook a jump box or cables to the bike and see if that does it. If your battery is more than a couple years old i'd say chances are good that is the issue

So, it's been over a week and I guess the bike is still just sitting around?

I had a smililar issue. I pulled the covers and started mussin and it was wiring harness for starter. Too hot - expanded I'm guessing. Good luck.

Check the starter switch and that the contacts are clean,n making connection.
nothing fried in there, a fuse wont blow when this happens.