Wiring harness and electrical woes..

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Jul 18, 2005
so im at my ends.. i have a stock 74 850 and its about time the harness gets redone.. ive seen some pics on here that some guys drew up with their boyer units and everything.. basically im creating a wiring harness for a stock system, and then next year i will be creating one for the upgraded system (boyer unit, etc).. this will be a professionally drawn cad drawing that ill be doing and if anyone has any inputs, ideas, or ways to cut down on the amount of wiring, i would appreciate it.
im trying to create a small box that will house the wiring relays, fuses, connections, that will go next to the battery instead of in the headlamp. the handlebar switch lines will probably still connect in the headlamp, but im not totally sure on that.. like i said, if everyone gives me input, i promise ill make a nice simple wiring harness that works!

thanx in advance!

I recently rewired the front end of my 72 Commando, when I converted it into a cafe racer style. The bike already has a Boyer unit, and was wiring with all original harness with a total bird's nest inside the stock headlight. My cafe fairing comes with a "pancake" headlight, with no room for any junctions. I used a small black plastic box from Radio Cottage (supplier of Lucas-related components, my funny!). And a simple terminal strip inside, along with a flasher can and a few terminal. Still a bit messy in there but a world of improvement over the tangle and bullet connectors inside the old headlight. I did not make an official diagram, but I have some notes. Planning to do a proper CAD drawing at some point.

1. You may be able to see some details on my site www.stuartostroff.com.

2. I will have some time next week-end and can chat with you.

Stuart Ostroff Phila, PA

On my 850 Interstate I mounted a small six circuit fuse panel (from Advance Auto Parts) on the back of the air box in the battery compartment. I fed the common connector from the battery and isolated fused circuits for the main ignition, the headlight relay (mounted in the headlight) and the horn relay (mounted behind the battery box). This is not as robust as the stainless steel Centech AP-1 fuse holder, but was smaller and cost less than $10 compared to $50 for the Centech. It converts the system over to blade type APC fuses which are more readily available than the glass ones found on the original harness.

I also made up a small aluminum L-shaped bracket to mount the Podtronics regulator/rectifier alongside the battery. It attaches to the bolts holding the top sidecover bracket. I used longer bolts, hex nuts for the side cover bracket, then slid the rectifier bracket over the protruding bolts and secured with wing nuts. That way I can pull the rectifier out of the way for easier access to the battery.

I have also converted my cafe racer to Ducati switchgear after losing the mount for the Lucas switches when I mounted a Brembo master cylinder. To connect these to the Norton harness I used Packard/Delphi Weatherpack connectors. These were probably overkill, but with their silicone seals are definitely lifetime units. Much better than Lucas bullet connectors.
Since you are on this side of the pond, check out http://www.britishwiring.com/ before you order. They may save you a little money over the shipping costs and you can keep fairly close to the orginal wire color scheme.
Nice web site. This one's a keeper. Thanks.
Thanx feliz...


Ive gone and sorted out some parts (new junction box, wires, connectors, etc.), and im stuck wondering a question.. has anyone converted over to using a negative ground instead of a positive ground that these bikes use? is it really possible to do it using the rectifier and diode and capacitor, or only using the boyer system..

i think i might only do the front section of the bike and leave the rest till next year when i have the boyer unit

let me know

Driggs said:
.. has anyone converted over to using a negative ground instead of a positive ground that these bikes use? is it really possible to do it using the rectifier and diode and capacitor, or only using the boyer system..

It should be quite easy to convert to negative ground, as far as I am aware the only polarity sensitive component which would require replacing in the standard setup is the zener diode. I'll be rewiring/sanitizing the wiring on my bike in the very near future and I may change to negative ground - but is there any advantage?
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