This flasher was originally designed to be used with the Hella Bar End turn signals that are typically seen on pre-1970's BMW's. The difference that this flasher has when compared to the stock units originally supplied, is that it is solid state (electronic) opposed to electromechanical. The advantage this offers is that I was able to design a circuit that has the same flash rate for 6V or 12V applications using the same part. I did this as some of the vintage motorcycles had upgrades to 12V systems. The electromechanical flashers would work for either 6V or 12V. This means that you need a different part depending on your particular battery voltage. The flasher shown below was designed for mounting inside the headlamp using one of the headlamp mounting bolts.

The flasher has two wires for connecting it up to the blinker system. The red wire is connected to the positive switched voltage. The black wire is connected to the blinker switch. The wiring diagram below shows the typical BMW bar-end blinker system. This same system may be in other motorcycles as well. Terminal 15 on the terminal board in the headlamp is +6V (or +12V) that is switched on when the key is inserted. The red wire connects directly to terminal 15. The black wire exits the headlamp, runs down the handlebars and connects to the turn signal switch (this requires an additional length of wire that is not supplied). Notice the lamp in each bar end turn signal is grounded on one end. This ground is connected via the bar end signal housing and handlebar through the frame back to the battery negative terminal. When the switch is actuated, either the left or the right turn signal bulb is connected to the black wire of the flasher completing the circuit and causing the bulb to blink.

The photo below shows the flasher mounted to the side of the headlamp.

Installation notes:

1. The flasher can tolerate a short duration reverse voltage. This can occur if the wiring is reversed. When the wiring is reversed, the turn signal that is selected will remain on (no flashing). Simply reverse the wires and the unit should function properly.
2. The color-coding of the wires is meant to indicate that the red wire needs to be connected to a more positive voltage than the black wire for proper operation. I bring this up, as the flasher will work on other blinker systems. In some antique vehicles the electrical system has a positive ground. This means the battery positive terminal is connected to the frame (ground). In this situation you would connect the red wire to ground (more positive voltage) and the black wire would go to the switch. I would be glad to review your particular wiring diagram to help with the proper installation of the flasher. Contact: beemererik@bellsouth.net
3. The flasher can be damaged when voltages in excess of 20V are applied.
4. For safety, you may want to install an inline fuse if there is not one in the blinker circuit path. Size of the fuse depends on the application. 5A slo-blo or greater should be sufficient for the typical vintage BMW applications I have encountered