Friday, May 29, 2015

Electrical Pt II - Building the Harness

My training in electronics is limited to classes taken many years ago although I still know what the basic components do and how to construct a wiring diagram. I also have a friend at work who is a EE who gave me pointers on things I couldn't figure out. There are also many sources for diagrams on the internet which I drew on to figure out the details of my setup. Below is my diagram in its seventh or eighth revision. Disclaimer……this diagram has been connected and everything appears to work fine but the bike has not been run. USE at your own risk!!!!! A Follow up post will provide an overview of its function. 

Wires were all cut to length and taped into place to understand how pieces fit into the various sections of the harness. Once this was completed the harness sections were taped together for shrink wrapping. Bullets were soldered on and a final sheath, which replicates the stock BSA look, covered all exposed wiring. Large sections of the harness were made first with smaller sections fit after they were in place.

Fuse panel, Sparx unit and relays. 
A small Lithium Ion battery will also fit into the battery box.

The coil & horn assembly ready to mount. 

And mounted......

Wire tied and ready to go. 

After the lights, horn and ignition tested out alright everything was cleaned up and wire tied into place. The horn & kill switch relays fit under the seat and the fuse box, sparx unit and Lithium Ion battery, which I have yet to purchase, fit in the battery box. A toggle switch is fixed to the seat mount. When the switch goes on everything works. There is no shutoff for the lights only a dipper. Headlight and taillight are LED units used for brightness & low power draw. Although I have color coded the wiring with paint blotches I am planning to buy a small label maker to identify things better. The future owner will appreciate this attention to detail – if I can ever get myself to part with the bike…. 
Ever wonder what was in a Lucas brake light switch? 
I did't until mine wouldn't work. Now it does. 

Headlight mounted & wired with new LED's. 
Heavy plastic wrap to main harness is visible on the lower right. 

And the opposite step final assembly. 

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