Wiring harness

A while back I put a new wiring harness on my bike.
There are so many unused wires that are only needed on the Police Bike version.
Made the whole business of hooking her up more complicated and all the extra wiring hanging around not pretty.
Since the number of Police Bike restorations going on out there probably could be counted on one hand I would think the basic replacement harness would avoid all the uneeded
wire and when needed could be a special add them.
Does anyone know of a replacement harness available without the Police stuff?

Bob

Unless you are looking for a 100 point restoration, I would say it is better to make your own, not only will you have the proper connections to the latest rectifier regulator, you are not forced to put it in a location dictated by the harness, the same holds true for electronic ignitions, LED lights and going to a proper negative ground.

Jean

FWIW, If you have the harness all hooked up on the bike and then start unwinding the tape, it doesnt take very long to go thru in sections and remove the wires you don't need. Don't take it off all at once but do it in sections. It is easy to keep the wires all in place, keep track of colors so you know what you are removing and then wind some new tape on that is nice and new. I peeled back about a foot, removed unwanted wires and then taped the section back up. If you are not sure what you want to remove you could take the tape off, put on a wire tie every now and then to hold it together and then trace out the wires while you are looking at the whole thing naked.

I agree with Jean that building a harness is a good way to go, but if you don't feel up to that the above process will give you a lot of the information you need to put one together and if you don't get around to it, you will have at least gotten rid of a lot of junk. I would not attempt this with the harness laying on a bench as I think it would be more difficult to see where to leave wires exiting the harness, etc. I think this would be a good exercise before building a custom harness unless you have enough experience to know exactly what you want.

However to answer your question, no I am not aware of any harness available without the extra stuff!

Russ

Agree on that, far too many dead end connectors on the stock harness particulary if you run minimal equipment. As a pre-caution, I slip a bit of heat shrink tube over all the redundant bullets as am insulator and reminder that these wires are not running anything. Personally I'd go with a custom harness but for re-sale value, a stock harness that hooks up all the electrical fruit is probably worthwhile.

Mick

I like the stock harness; all the wire colors are correct and there are no surprises. Everything is as per the service manual - for you AND for any future owner. So what if there are a bunch of wires that aren't connected to anything? Who cares? Look at cars. They are the same way. If you don't have all the options, there are wiring harness wires that don't connect to anything. WHat's the big deal? At worst and if you really feel that way, connect all the appropriate wires and clip off all the others flush with where they exit the harness.

A custom harness is both easy to build and has the potential to be much better than OE or aftermarket clones. As many have pointed out the OE or clone has circuits that fit multipul market places and as also has been pointed out, whether or not you use a given circuit it may be powered up and present short potential if not "capped off" properly. Another observation is that the OE harness has "bunches" of bullet connectors making for a very pregnant look under the tank and in the headlight, never mind the battery box area.

Going to a negative ground could save your bacon if you were ever to leave you bike for a battery replacement. You should label the battery area, with + or - ground information in any event to CYA.

Building a wiring harness may seem intimidating, taken as a whole, but if you consider the individual circuits and use some common sense where you run the wires you will find that building a harness can be very satisfying and can add to the esthetics and functionality of your machine; do carry a 14 ga grpund to every current comsuming point. For example, I ran a two spare power and ground wires to the headlight so that I could power my GPS and I-Pod. I also created a circuit off fthe battery (with fuse) for my heated vest, which extends the riding season into December, and picks it up in March; I did add the sparx 220 Watt alternator.

So, don't think of your wiring harness as a spiders nest, think of it as a group of circuits that get your jobs done.

RS

That's what I've been doing- one circuit at a time.

I have had trouble with every harness I have purchased. mostly poor grounding. I am going to make my own for the MK3, and eliminate go nowhere circuits.

moond850 said:

I have had trouble with every harness I have purchased. mostly poor grounding. I am going to make my own for the MK3, and eliminate go nowhere circuits.

Click to expand...

After eliminating all that I concidered unnecessary, like capacitor, warning light can, adding solidstate charging and ei ignition, I find that there is not a hole lot left out back. The Headlight harness, however, could be retained and adapted to as needed. being a separate loom.

Being a non MKIII type of person, I still feel that this particular issue could surely cross over.

TMS Wiring in the UK makes a harness without the police wires. Martin White is the sales guy -- sales@tms-motorcycles.co.uk

MC.32 MAIN HARNESS PVC £53.00
MC.32PB MAIN HARNESS CLOTH £66.25
MC.32H HEADLAMP HARNESS PVC £21.25
MC.32HPB HEADLAMP HARNESS CLOTH £26.45
PRICES ARE PLUS POSTAGE & VAT

Ive done it both ways, custom and purchased. On a Commando so many wires are unnecessary and that multi bunch connector under the tank
is a pain. If you are going for a dead stock bike then buy the proper loom otherwise make it yourself. A rider will need some relays and home
run grounds so it only makes sense. You can also increase the size of conductors if you wish. Going to negative ground good idea too but since
I have several brit bikes better for me to keep them all + earth for sanity's sake.

Here is the wiring diagram I have for my bike. I bought a headlight wiring harness and I ran the handle bar switch leads into the headlight instead of under the tank.
Everything else is custom and works great. Fuse-blox is the fuse panel and has some nice features like a relay that turns on everything for you when you turn it on. So, as you will notice the ignitions switch only turns on the fuse panel. There are no relays wired in and I am running full amperage through the Lucas handle bar switches. They are really well made switches so cleaning the contacts makes them work real good.



I used old wiring harnesses to keep the wiring colors as close to original as I could.
Dan.

Or buy an original harness with all the wires in it and take out the ones you don't need, TMS charging more for less - brilliant sale technique!

Hi Dan,
Sorry, this is a little off the original subject. I'm wiring up another bike from scratch, and I'm hung up on figuring out how to properly wire turn signals with a single dash tell-tail light that would indicate when either side is flashing, and I'm NOT an electrical whiz. Looking at your schematic, wouldn't the blinking +12 volts from one side go thru your turn signal warning light and work the other sides lights as well?
Bill

Bill,
That is what I thought too. It would light the other side through the warning light if the filament was large enough but as it is it only grounds through the other side and does not supply enough current to light the bulbs. That is the way Norton does it as well so I just kept it the same.

I tried to keep everything as close to stock as I could with the changes that I did make. The colors should hold and the connection picture is as it is on a regular Commando schematic. I didn't actually use a big plug block though just regular butt connectors.

One cool thing about the Fuze Block (http://www.fuzeblocks.com/) is that it has a relay that turns everything on but if the relay goes bad you can just move the fuses over to the next row that is powered all the time. Like, if your battery was too low to turn on the relay you could just move the ignition fuse over one row and effectively hot wire the bike to get it going.
Dan.

Thanks Dan, although I'm still puzzled if that approach would work on my non-standard R90s, with LED turn signals and a 3W turn indicator warning light. I've been in touch with Rick at Motorrad Elektrik and he's sending a flasher/relay that he assures me will work. We'll see.
That is a nice looking fuse block, and a very nicely done electrical schematic.
Bill

I used old wiring harnesses to keep the wiring colors as close to original as I could.

Click to expand...

I use original color codes with new wire from British Wiring. You can get all the original wiring colors with modern wire and insulation. This makes it simpler to trouble shoot by someone who has an original wiring diagram and is not familiar with how you designed the harness.

+1 on the modern insulation with original colors! I didn't know about British Wiring when I did mine.
Dan.

Bob,

I'm in agreement with the members who recommend you doing a custom harness. Since you are only making one of them, construct it on the bike in a point-to-point fashion. You can split the backbone bundle into two. making a neater loom. Construct the loom with the air cleaner in place, as this is a crowded area for wires, and you want to insure easy access to the filter. British Wiring has all original markings and colors. Consider the following points:

1. Now is the time to consider a negative-ground conversion. If your bike is a Mk3, you'll have to replace (or eliminate) the assimilator; Old Brits have them. In any case, use black wiring for ground, not the original red; this will avoid the red-wire ambiguity when you add aftermarket devices to the loom. Otherwise, you're free to use the original wire markings regardless of your choice of polarity.

2. A custom loom allows for relays (horn and lights, e.g.) and a real fuse block using modern blade fuses.

3. Rather than tape, use the flexible bundling tubes used in cars. It's neat and allows access to the entire bundle when needed.

4. Document as you go. I found it more useful to construct a harness diagram rather than a schematic as I wired my Mk3.

I'd be happy to send my harness diagram to you; just be aware that it is specific to my enhancements (3-phase alternator and rectifier/regulator, negative-ground, new assililator, relays, fuse block). Send me a PM; we're in the same time zone.

the New Lucas wiring looms are Excellent cloth covered with all the correct terminals and connectors

also supplied with an installation wiring diagram so very simple to fit