I just picked up my first moped a couple weeks ago and have been blissfully tinkering around with it while waiting for some money to free up for a helmet and registration so I can drive it to and from work (6 miles both ways). The bike is a 1981 Tomos Silver Bullet (TS, I guess because it has stock turn signals). Runs really good right out of the gate and only has 1700 miles on it, seems pretty low for its age. So far I have cleaned it up, started polishing, fixed a leaky 2 stroke oil hose, tightened some loose nuts/bolts and now I am trying to get the electrical system up to 100%.
Right now the headlights, breaklights, horn and oddly enough the left front turn signal only are functioning, but all are dimming and brightening with the rmps of the engine. The one working turn signal will only come on when the engine is really cranking, doesn't work at idle at all. Upon inspection I found one green wire under the rear fender that was damaged and exposed, but not totally disconnected. Also inside the control switch for the turn signals and engine run/off, there was a piece of solder that had come loose resting between two of the turns signal control prongs. Took that out and cleaned all connects with DeoxIT cleaner (highly recommended for all vintage electronic cleaning). Also, checked all the non-functioning turn signal bulbs and wires and they all seem to be good. Which brings us to the main topic...
The infamous and evasive Tomos BLACK BOX that houses the electrical components. I've read a few threads on here about the black box and its contents, but mostly it seems to be somewhat unknown territory, so I thought Id share my experience and post some picks to help shed some light.
Firstly, the box from my 1981 most definitely contains a 6v battery pack made of 5 1.2v cells connected in a 3x2 stack, just like a standard 6v RC battery you can buy at a hobby store or online for a radio controlled car, plane, ect. I yanked that battery out and it is TOTALLY dead, no charge at all (it is like 30 years old). So, I am going to order another 6v pack from ebay for like $12 and install that. One really weird thing is this little, round black plastic piece that was connected to the bottom of the battery, in the middle of the chain of cells, on a negative terminal. It has two yellow wires connecting the other end to the circuit board. After Googleing the part numbers on it, I found a site that talked about the part also being used in washer and driers as an electrical thermostat. So, Ive come to the conclusion that its function is to break the connection between the battery and the stator (charger in this case) if the battery gets too hot.
If all goes as planned I'm thinking that the turn signals and hopefully all the lights will work with the new battery independently from the rpms of the engine and the engine will charge the battery.
I'll post pics of the box, battery and thermostat if anyone is interested. Sorry if Im rehashing old stuff here, but I scoured this site and couldn't find anything this specific on the topic.