*** Updated for February 2025 ***
I first published this page in 13th February 2021.
My new schematics have been drawn from scratch and I have included:
- better resolution – they can be printed on A2 paper (23.4in x 16.5in) without any loss of quality.
- sized for UK and Europe – originally the page was sized for US Legal (14in x 8.5in) paper, and resizing for A4/A3/A2 standard didn’t work.
- cable colours were confusing – it was difficult to see what was the dominant colour ‘vs’ what was the trace colour.
- for MK3 move the key switch from the right to the left side of the page.
- show the warning lamp colours.
- lighter background – ideally there would be no background, but as there are a lot of white cables this would make it difficult to read. I have lightened up the background, and outlined the white cables, it works much better for printing now.
- make points/condenser arrangement clearer.
- show terminals on turn signal flasher unit.
- group additional fuses on early MK3 schematic.
- improved labelling.
There are numerous other small improvements too, which make the schematics easier to read.
The question often comes up, what is the cheapest, easiest way to upgrade a Norton Commando charging system?
In my opinion, a great option is to go for a three phase stator:
- Lucas RM24
- 3 Phase
- 10.5 amp
- Part Number LU47252
- Also found under Part Number WW10193L
This stator has roughly the same output as the standard RM21 that came on the bike – however, the rated output is produced at a much lower RPM making this an ideal solution for around town and in stop start traffic conditions.
As always, I would recommend that you ride with your headlight on, as this will always help with the longevity of the components that make up your charging system.
The factory standard zener diode can handle this with no problem at all, so no need to change that.
However, it will be necessary to change your factory rectifier from a single phase one to a three phase one.
Fortunately, these are available at a very low cost indeed (around 10 dollars) – plus you get the advantage of something that is encapsulated in resin so is shake-proof (something that the original Lucas single phase rectifier suffered with.
A good three phase rectifier would be something like the 36MT60 – it is a very common component, and there are plenty of places online that sell them (you are not limited to classic Norton dealers)
The component looks like this:
Don’t be worried about wiring it in – it really couldn’t be simpler!
Warning Light Assimilator
The factory warning light assimilator is not compatible with most modern regulator/rectifiers and the PODtronics is no exception so it has been removed from the schematics.
Plus, there is the matter of what the WLA is actually doing, and how much use that is.
The WLA is looking purely for some AC output from the alternator stator (about 6 ½ volts AC) it is not designed for a three phase stator either.
It gives you no information about the charging (i.e., the regulator (zeners) and rectifier)
It gives you no information about the state of the battery.
Charge Warning Light
I have taken the liberty of adding an ICM Charge Warning Light to the schematics – I can certainly recommend the Improving Classic Motorcycles charge warning light as a brilliant alternative.
I use them myself, and have had a good experience with them.
The nice thing about the Improving Classic Motorcycles unit is that you can retain the original warning light – so it looks totally factory (this for me is an important factor with the MK3 with it’s quirky little instrument panel).
It gives you a lot more useful information about the state of the battery and charging system compared to the standard assimilator unit, which looks for AC output from the alternator stator only.
1968 Norton Commando Wiring Schematic + three phase alternator
These are the pre-1971 bikes and have the ammeter in the headlight shell, as well as the Wipac Triconsul type handlebar switch.
The wiring is very simple, and more like the Atlas than what came to be familiar with the Commando.
Note that I have included the Front Brake Switch as standard – this was a US requirement, that didn’t appear on the earliest UK bikes.
1968 Norton Commando Wiring Schematic + three phase alternator PNG 5600×3960
This diagram is also downloadable as a PDF from HERE
1971 Norton Commando Wiring Schematic + three phase alternator
This is often referred to as the “Interim” model.
It is distinguishable by the three pin master switch (ignition key switch) which was Lucas part number LU39565.
These were made ONLY for the Norton Commando, and are no available as an aftermarket replacement.
If you are not comfortable rebuilding the switch, most people choose to go for the LU30552, which IS readily available.
You can find an article on ignition switches here, that may be of interest.
1971 Norton Commando Wiring Schematic + three phase alternator PNG 5600×3960
This diagram is also downloadable as a PDF from HERE
1972 onwards Norton Commando Wiring Schematic + three phase alternator
The 1972 onwards schematic covers 750 and 850 bikes and has the much more familiar four pin master switch (ignition key switch)
1972 onwards Norton Commando Wiring Schematic + three phase alternator PNG 5600×3960
This diagram is also downloadable as a PDF from HERE
This would also be a better system than the high power single phase stator that was fitted to the MK3.
Dropping one zener, and moving the remaining one to the DC side as shown below will up the system voltage by 0.7 volts – sounds like a silly little number, but that is actually quite useful, and was an achilles heel back in the day that upset the early electronic ignitions.
MK3 Commando
During the manufacture of the MK3, Norton and Triumph were coming together, and they were often feeding from the same parts bins.
We have noted some anomalies between the handlebar switches while the MK3 was in production, as they frequently used the Triumph T140E switches, which look the same, but have a couple of small wiring differences.
Left handlebar switch the U (blue) used by Norton (and illustrated in the factory workshop manual) has been replaced with a UY (blue/yellow) cable. This connects to the U (blue) of the right handlebar switch inside the headlamp bucket.
Right handlebar switch there is no S (slate grey) instead, the single “hot” negative from the pin 2 of the Master Switch (ignition key switch) is jumpered for both engine run/kill switch and the starter button.
Another element of the MK3 that sometimes causes confusion is the wiring around the Warning lights.
The factory workshop manual shows the following:
I have covered this in more detail in a separate article, which can be found here.
But in short, the cable colors used for the sub-console wiring harness were not the same all the way through MK3 production – so certainly something to watch out for!
1974 Norton MK3 Commando (Early) Wiring Schematic + three phase alternator
1974 MK3 Early Bikes – there were around 2,000 bikes that were built around the December 1974 timeframe that have three additional fuses that can be found in the headlamp bucket.
1974 Norton MK3 Commando (Early) Wiring Schematic + three phase alternator PNG 5600×3960
This diagram is also downloadable as a PDF from HERE
1975 Norton MK3 Commando Wiring Schematic + three phase alternator
This is the most common configuration, and takes us through to the final Commando that rolls off the production line.
1975 Norton MK3 Commando Wiring Schematic + three phase alternator PNG 5600×3960
This diagram is also downloadable as a PDF from HERE
1975 Norton MK3 Commando (Canadian Market) Wiring Schematic + three phase alternator
For the Canadian Market, there were legal requirements around the headlamp being on while the engine was running.
A different Master Switch (ignition key switch) is fitted in order to adhere to law in Canada. More info is available here in a separate article.
This is covered in the Factory Wiring Diagram, by notes.
The Canadian key switch LU30825 is not available, and must be rebuilt manually.
1975 Norton MK3 Commando (Canadian Market) Wiring Schematic + three phase alternator PNG 5600×3960
This diagram is also downloadable as a PDF from HERE
NOTE:
A couple of points about the way these diagrams have been drawn:
- The diagrams on my site are schematics – the components are not drawn in the physical location on the bike. Instead they are drawn in locations that make the diagram the easiest and most logical to follow.
- Where the same colour wire goes in to and out of a single connector, that connector has usually been omitted from the drawing.
It’s obvious on the bike, is easy to spot and easy to troubleshoot.
Leaving them off the diagrams makes them a LOT easier to read, and considerably less cluttered. - Wherever the earth or ground side of a component goes back to the battery, the drawing shows a red earth symbol:
In reality, this could be connected either to a red wire in the bike’s wiring harness (loom) OR it could be attached to the frame or engine of the bike.
I have shown the red earth symbol each time in order to massively simplify the diagram, and make it a lot easier to understand for everyone.
I have also coloured them red as a gentle reminder that these bikes are wired positive earth!
Categories: Aftermarket Upgrades, motorcycles
Grant,
I have a 1974 Commando that I want to keep with positive ground. I have the 3-phase alternator with a Mosfit regulator and now installing a tri-spark ignition. I am also going with the icm unit along with the oil pressure sending unit.My question is how to connect the wire going to the electronic tach.12V single coil.
Any help would be appreciated
Thanks
Mike Yingling
Great to hear from you Mike!
I have made a wiring diagram for you, and put some thoughts about your electronic tacho here:
https://granttiller.com/custom-norton-commando-wiring-diagram-mike-yingling
Hopefully I have captured everything, but if there are any tweaks or changes, please feel free to reach out!
Grant
Hi there. What a brilliant and helpful page, Thank you so much!
Am i right, if I only need to change the alternator(stat or), and rectifier.?
And that I can leave the roter, and that there is No need for the podtronics box?
Would be so satisfying to change as little as possible on my 71 fastback.
Hi Lars,
Absolutely right!
The rotor can stay exactly as it is – they do lose their magnetism eventually, but provided it can hold it’s own weight if you hang it off a screwdriver, it will be fine!
Make sure you buy the 10.5 amp LU47252 and NOT the high powered LU47244 and you should be good to go!
Hope that helps,
Grant