I started the process of breaking down the BS-7 tonight. Maybe I was just having a rough night, but it sure seems like this little monster is way more complicated than my other bikes of this same vintage. At minimum, there is roughly twice the amount of wiring since this bike came stock with turn signals front and rear, and an electric starter. Which I didn't realize until I finally understood what the service manual was referring to as the "cell dynamo."
It also has this jewel mounted to the frame. Seems to be a combo voltage regulator, fuse box, and cell dynamo relay: