Hello...
I just picked up a '76 CB550. While I've been riding for nearly 20 years, I have rarely, if ever, worked on my own bike, and I have my very first big headache with no idea how to fix it. I bought it not running. The PO says that one day he was riding along, the headlight and gauges dimmed, and it sputtered and died, never to start again. I bought a multi-meter and tested the coils, and they showed the correct resistance. haven't tested the rectifier or regulator yet, because I have no idea where they are or what they look like.
Here's a pic of the bike on the trailer, on its way home.