I recently changed parts between the 2 XB-600's I've got to make 1 great bike. I learned (the hard way) that though both bikes look the same, some of the parts are different. Differences I noticed range from: rear wheel configuration & parts, front shock size, tube size, etc...
I've tested all the wires coming from controller, replaced the fuses, checked the schematics, unplugged the right break, and still can't get power to the motor. The lights work fine and everything else seems to be in order.