Motorcycle Repair: 1976 Yamaha electrical problem, dual overhead cam, switch wiring

Question
I recently purchased this 1976 Yamaha DOHC 500, not sure what the DOHC stands for, but it is in almost excellent condition and only has 7,000 miles on it. It has been in storage since 1989, and I assume carbs and points need replacing, however, when I hook a battery up, and turn key to start position, it blows the main 20amp fuse every time. I have checked wiring and don't see any shorts, could it be the coil? No other repairs have been done on this bike in its life (i bought it from original owner)

Answer
Hi Eric.

First thing, DOHC stands for Dual OverHead Cam.  Much better than SOHC (Single OverHead Cam).

The fact that the main fuse is blowing when you turn power on, indicates that there is a short in the main wiring harness.  If you are not capable of or unwilling to chase down the short, then get it to a shop and have them find and fix it.  If the short isn't fairly obvious then it is going to take a lot of time to find the short.  You will need the schematic and a multimeter to find the short.  Chances are, the short is in fact in the switch wiring and circuit, since it only blows the fuse when you turn the switch on.

Start with that and let me know what you find.
Good luck and ride safe.
FALCON