Motorcycle Repair: top brush wire blows 20amp fuse, 1981 yamaha 650, stator

Question
chris i have a 1981 yamaha 650 and if i disconnect the top brushwire it starts up but when i connect the top brushwire and turn the switch on the 20amp fuse blowes right away can you please tell what is wrong the brushes are down by the rotor and stator thank you

Answer
Hi Harry.
 You have a short in the system on that particular part of the circuit.  Somewhere along the way, something is grounding out where it shouldn't between power and that brush.

 Check that line from power to brush.  Then see if something is contacting the brush where it shouldn't.

Find that and your problem is solved.
Good luck.
FALCON