Motorcycle Repair: 1980 Suzuki GN400 Electrical, suzuki gn400, turn signals

Question
I have a 1980 Suzuki GN400 that I'd bought as a project bike.  I got everything to work on the bike (runs well, etc.) except all of the electrical doesn't work aside from the spark in the plug.  I put a fresh battery in and tested past the one and only fuse that I can find which is connected directly to the positive wire hooking to the battery.  The tailights and headlight don't work nor do the turn signals, display lights, or anything else but the spark plug.  I'm not sure where to start?

Answer
It sounds like something has come loose or has corroded in the wiring harness. Unfortunately, unless something is obviously broken or melted in the wiring, this could be hard to get right without a wiring diagram. I would go over all the connectors and make sure they are clean. If I can't figure it out from there I would get a wiring diagram (usually in the service manual) and trace each circuit to make sure its correct.