My race bike has a battery eliminator and the road a normal gel battery, they do need a 12v feed.
As for testing the motor, there must be a way but i'm not an expert i'm afraid. I always carry a spare motor and switched the ypvs controller from the race bike which gave me that bad news. If its the controller, i was put onto 2t racelab which are Athens. He did an amazing job and quick turnaround for sensible money. Controllers are quite hard to get hold of and command quite a bit of money with no guarentee.
If its the motor itself, they are quite easy to get hold of through fleabay or from here, my new spare came from Malc.