I put together a series of pages about BMW airhead motorcycle electrical systems. It strikes me that electricity in general, and motorcycle electrics in particular, are dark mysteries to many, so I thought I’d shine some light [puns intended 🙂 ].
Lack of understanding hinders confidence when diagnosing and working on electrical projects. As these bikes age, the electrical system is prone to problems as corrosion and neglect makes them behave badly. More owners are having more electrical problems but seem less able to get to the root cause of the problem.
I think one tool that many avoid using is the wiring diagram. The spaghetti of lines, symbols and notations makes the eyes glaze over. “Oh goodness, where do I start?” is the common response to the advice, “Look at the wiring diagram.”
I’m not an electrical engineer, but I have taken time to learn the basics, have collected comments and input from well respected airhead mechanics and dug into how BMW applied electrical theory when they designed the /5 electrical system. I’ve learned a lot from various reference sources that are scattered about the internet, so my articles include a bibliography of various useful resources. That way both you and I have a nice set of reference materials to consult when problems come up.
I have published three articles (so far), Basics and two about the /5 series: 5 Series Electrical Circuits and, 5 Series Electrical Components. I chose the /5 series to start with because I believe it’s the most popular airhead series for restoration.
I hope to write an Electrical Circuits and Electrical Components document for the /6 and /7 series up to 1984.
Here is the table of contents from the first three documents.
Airhead Electrical Systems-Basics
- Learning The Language of Wiring Diagrams
Airhead Electrical Systems-5 Series Circuits
- What Makes a Closed Circuit?
- 5 Series Wiring Diagram Components
- The Battery (+) Terminal Wires
- Ignition Switch Circuit
- Ignition Switch-Park and Headlight Switch
- Turn Signal Circuit
- Charging Circuit
- Starter Circuit
- Engine Ignition Circuit
Airhead Electrical Systems-5 Series Components
- Capacitors, Coils (aka, Inductors), Diodes, Resistors, Transistors
- Switches & Relays
- Charging System
- Starter Relay, Starter Motor and Solenoid
- Engine Ignition System