XJ550 Seca electrical issue

Hello, new member, my buddy and I had found a few old motorcycles that this older gentleman had in his shop for many years. He didn't remember when he actually bought them, but we ended up buying a 81 XJ550 Seca. The bike overall looked great compared to the rest of them. We brought it home and found that the electrical appears to have been messed with at one point and converted to only run off of a single 20A fuse. We bought a new battery and installed it just to see if we got power, as soon as we plugged it in my buddy noticed a flash, turns out it blew the 20A fuse. See pictures below of what we're working with, is there any reason someone would remove the 3 other fuses and just run off the single fuse? I have not replaced the 20A fuse with a brand new one yet, wanted to check first.

 

Reason? Sure...that person was an idiot.

You have some sorting to do. Start with familiarizing yourself with the machine.
Read This First
That link will get you started down the path to having a safe and reliable machine.

As to the lack of a fusebox, this is the recommended thing to do unless you are building a machine for shows.
HOW TO: Install an aftermarket fuse box
And why it should be done (and why the hack-job you're seeing was done).
Your Fuse Box -- A Ticking Bomb??? By: Rick Massey


Please make this the thread for your refurb so we can keep track of the histoy of your progress and don't miss any details that might help with fault diagnoses.
I can re-title it if you like.

Welcome aboard

 

This might be handy also..

http://www.lumien.se/stuff/xj550/XJ550ElectricalDiagram1.1.40.png

 

I expect that loose black/green wire should be attached to the fuel gauge sender btw.

 

Thank you, sure we can do that. We will go through the wiring to see what we can figure out with it. Hopefully they didn't completely destroy it.

 

the fuses work like this. battery wire red (large white connector with woven insulation coming from solinoid) to main fuse which goes to the ignition key. then a brown wire goes from key to fuse box and splits into 3 wires (reds)for the signal, ignition and headlight.