Here are copies of the colorised wiring diagrams I created, based on the original Honda black and white diagram for the UK-market 1978-82 C90. Earlier diagrams are available below.

If you aren't familiar with reading this type of diagram (it is not has hard as it first appears!) then you can read more about them here:

Honda C90 - electrical system overview

Electricity Learning the basics of automotive electrical systems, even the simple system used in the Honda super cub, was something I approached with a little trepidation. My schoolboy science got me as far as grasping that the electrons in conductive materials like metal can “jump” between atoms, displacing others in

The Small WorkshopNick

Complete wiring diagram (1978-82)

Subsystem diagrams

The diagram can be broken down into separate 'subsystems' to make them easier to understand. These are shown below:

Earlier 6v models (1964-77)

The early C90s had a side panel mounted ignition switch.

The C90 model introduced to the UK market in the the late 60s included a new central lighting control switch and a secondary parking light installed inside the headlight unit.

The parking light was introduced because of a UK regulation that requires vehicles to display parking lights when parked on a road with a speed limit greater than 30 mph. A corresponding change to the ignition switch was also required, and the new switch adds a new parking switch position and has 4 wires rather than two (the additional brown/white and brown connections are for the front and rear parking lights respectively).

1966 wiring diagram

1973 wiring diagram (UK)