Originally Posted by Donkey Hotey
It's either the starter motor or one of the three cables.
If you want to really be doubly sure, disconnect one of the cables at the relay and touch it to the remaining one. If the engine doesn't crank, you've eliminated everything else on the bike. That's the simplest circuit: battery straight to the starter. The whole rest of the bike could be missing but, that should spin the starter.
You said you disassembled the starter and verified it was good. How did you verify? Did you check each set of windings with an ohmmeter or just get it to spin on the bench when connected to a battery?
You may have one or more shorted or open windings in the motor and once it spins to those, it will stop.
I said before the starter turns the engine over and even starts the bike just fine when powered from jumper cables directly to the starter. When I opened it I rebuilt it with a rebuild kit, even though everything looked like new in there.
I also replaced the cable from the relay to the starter. I will try the battery straight to starter method.
I ordered both relays yesterday.