Custom Norton Commando Wiring Diagram – Richard Dodds

Grant Tiller

Richard Dodds has a Canadian Spec MK3 Commando, but has made some modifications to it inline with modern motoring and reliability.


First up, Richard has fitted a Tri-Spark electronic ignition to his bike – this is a great pairing for a MK3, as the circuitry really minimises kickbacks, so it is much kinder on that delicate sprag clutch!

You can find the Tri-Spark website here.

Grant Tiller

The Tri-Spark unit is a one box solution – all the gubbins are mounted inside the points cover – no additional black box to try and hide under the tank, and very very simple to connect up.

The wiring is as follows:

  • Red wire – this is the positive feed to the Tri-Spark unit. Most people attach this wire to one of the two fixing posts inside the points cover. I would personally recommend running an additional wire up to the coils and have drawn it this way on the wiring diagram.
  • Black/Yellow – this is the negative feed to the Tri-Spark unit. This joins in to the White/Yellow that is the kill switch on your right side handlebar switch (the Ballast resistor is no longer required)
  • Black/White – this is the negative supply FROM the Tri-Spark TO the coil.

You’ll note in the wiring diagrams below that the Ballast Resistor and Condensers have been removed as part of the conversion to Electronic Ignition.

Two major benefits of the Tri-Spark:

  1. a very low operating voltage – as low as 8 volts means your bike will still run with a less than optimal battery and charging system
  2. circuitry performs the electronic equivalent of advance and retard to make the bike easier to start and stop the possibility of kick-back. This makes it gentler on your knees, and kinder to electric start systems (aka the delicate Commando sprag clutch)


In lieu of the twin 6 volt coils, Richard has fitted the dual output single tower coil from Colorado Norton Works (it’s the brilliant Crane Cams unit) and looks much neater.

Grant Tiller


He has also fitted a 3 phase Lucas alternator – a nice choice for superior charging in modern traffic conditions.

Grant Tiller


To go with the three phase Stator, Richard has fitted a Podtronics 3 phase regulator/rectifier in lieu of the half wave rectifier and twin zener diodes of the MK3.

This will bring the voltage up a little too!

Grant Tiller

Battery Status

Grant Tiller

Richard has fitted a SparkBright voltage monitor instead of running with the standard warning light assimilator.

Wiring Diagram

Custom Norton Commando Wiring Diagram – Richard Dodds PNG 3066×1841

Grant Tiller

7 replies

  1. Again, many thanks for doing the custom wiring diagram for me, have just laminated an A3 copy for my workshop wall.
    I’m afraid i’m not too clever with electronic stuff, so was hoping you could please advise me:-

    Deutsch connectors

    DT type is slightly bigger, has size #16 terminals and 2 wire sizes, 14 – 16 (with green bands on terminals,) 16 – 20 (plain terminals) . Rated at 15amps.

    DTM type is smaller, but also has a moulding each end for shrink wrap, which makes it longer. Only size #20 available. Rated at 7.5 amps.

    My new loom is made up with 20 awg size wire.
    As I already have a few DT type plugs I will use them and use the shrink wrap that has glue inside.
    I guess the wire to the headlight draws the most power? Just wondering what the typical amps through these wires is?
    I have the standard glass 35 amp fuse fitted, but would like to change to modern car type, but believe the 2 types are rated differently?
    Would appreciate very much any advice you can give
    Kind regards

    • For speccing out your connectors, take the worst case scenario:
      A quartz halogen main beam at 60 watts.
      You have a fully charged battery at 12.6 volts.
      …that means you are drawing 4.7 amps.

      In reality:
      A typical H4 dipped beam is 55 watts.
      Your Podtronics is putting out 14.6 volts.
      …that means you are drawing 3.8 amps.

      I use the smaller DTM connectors – that are rated at 7.5 amps in continuous use everywhere apart from the alternator wires – where I use the DT connectors which are rated at 13 amps.
      I use the nickel-plated solid connector pins, not the stamped ones.

      Check out the Deutsch Jiffy Splice – it is a connector that accommodates a single pin and socket and takes up very little space.

      The size 16 Jiffy Splice holds the DT connector size pins.

      Do bear in mind the difference between the US and UK way that fuses are rated:

      The British Standard used rated fuses by the current that would make them blow instantly.
      The American (and now international) Standard rates fuses by the amount of current they will carry forever.

      With larger fuses, it becomes an issue and you stand a chance of melting your wiring.

      For example, a Norton Commando factory workshop manual (written for the Brits with the British Standard in mind) specifies a 35 amp fuse.

      A 35 amp North American fuse is around double the rating of what a 35 amp British fuse would have been back in the day.

      And at this point, all the insulation would be melting off your wires before the fuse blows.

      The equivalent automotive blade fuse would be 17.5 amps but that value is not readily available – as a rule of thumb, I upsize to 20 amps for a MK3 and downsize to 15 amps on a pre-MK3 as these are standard values and are sold at every petrol station

      Always bear this difference in mind when reading the manuals, and replacing the fuses.

      How fuses are rated now makes no difference to the way the manuals are worded in the books we’ve all got on our shelves.
      If I bought a glass fuse from my local autostore today, it would be a 20 amp fuse, even though my manual calls for a 35 amp fuse.

      Also consider wire sizes, and remember that your fuse must always be the weakest link!
      The typical wire sizes used by Lucas that we see on our classic bikes, are rated as follows:

      44 strand
      44/0.12 (44/0.30mm) 22 amp

      28 strand
      28/0.12 (28/0.30mm) 14 amp

      14 strand
      14/0.10 (14/0.25mm) 6 amp
      14/0.12 (14/0.30mm) 7 amp

      9 strand
      9/0.12 (9/0.30mm) 4 amp

      Note 1 – the 14/0.10 was superseded by the 60s
      Note 2 – modern cables of the same spec are rated higher than the figures Lucas give (as shown here)

  2. Hi Grant,
    Thanks for all this useful information, which even I can understand. I was most interested in the Deutsch jiffy splice connectors but haven’t seen them here in New Zealand. They would be great for inside the headlight shell and getting thru the shell rubber grommet. There’s a place in Auckland that specialises in performance car electrics that sells Deutsch connectors, about 4hrs from here. Will pay them a visit. Just wondering what brand of crimping tool you use? The one’s I have seen here are very expensive, over $100 and only does one size terminal. I am currently also thinking of getting a Tri Spark mofset regulator, to keep as a spare incase the Podtronics one fails.
    Kind regards

    • I try to steer clear of universal crimping tools.
      For the Deutsch connectors I use this one – it only does Deutsch connectors:

      It is the HDT-48-00 made by TE (who make the connectors)

      It is spendy for sure, but I have done hundreds of connectors, and it is still as good as new and will probably outlast me!
      Link here

      I get a lot of my stuff from these guys – they are in the US, so I don’t know what shipping costs to New Zealand would be like:
      Worth looking at their website, even if it’s just for ideas of all the different connector types and sizes that are available.

      The new Tri-Spark reg/rec is a big step forwards.
      MOSFET instead of the old Thyristor based SCR technology means that voltage control is far more accurate.
      Still a little higher than I am happy with if you are considering lithium-based batteries.
      The downside for me is that, like the Podtronics (and many of the other reg/recs on the market) they are still short-type.
      That is to say, they dead short the alternator stator windings when no charge to the battery is needed.

      I don’t like this idea, and out of principle, will not install these on my bikes.
      I feel it is no coincidence that the number of charging issues have gone through the roof since the introduction of the reg/rec, compared to the last 40 years when everyone’s bikes have been totally fine.

      The only reg/rec type I like is the series-type.
      These open the AC circuit when charge is not required, taking the load off the alternator stator windings completely.
      I am looking all the time, but at the moment I still feel the Shindengen SH775 is the best available for our bikes.
      There is a great article on this site by Jean Des Rosiers which covers the Podtronics ‘vs’ the Shindengen

      Hope that helps.

  3. Hi Grant, greetings from cold wet New Zealand.
    Finally finished my Mk3 wiring project, the diagram you did for me has been a real lifesaver! I ended up cutting off all the nylon connectors on my original handlebar switches and the bullet connectors on my modified headlight wiring loom. I went with Deutsch DT connectors to replace these.
    Didn’t like the idea of all those bullet connectors inside the headlight shell.
    Everything went well, except my headlight wouldn’t work, I hadn’t pushed the contracts fully home in one of the Deutsch housings!
    Was just wondering if you can please help with the following :-

    I’m thinking of changing the Podtronics unit for the new Tri spark one and keeping the Podtronics one as a spare.

    Was thinking of finding a suitable led parking light bulb (9mm bayonet base) and wiring this to act as a daylight on light. Can’t seem to find any bulbs here in NZ.

    Can you please tell me, is the Canadian ign switch the same as the standard one? Andover Norton seem to have about 6 part numbers for the same switch?

    I have the following problem :-

    In park position I have front and rear park lights on, plus both tach & speedo lights on.

    Off is OK

    In ignition position,
    I have speedo & tacho lights on, plus a very bright tail light (looks like stop light is on)

    Lights on position,
    I have speedo & tach lights on, plus the same very bright tail light, and normal headlights (full & dip)

    Is there a better option for the Sparkbright light I have fitted to my console? It works fine most of the time, but every now and then it becomes unstable.
    Much appreciate any help you can give
    Kind regards

    • Great to hear from you Richard – and it’s good to hear that the diagram has been some use to you!

      The Tri-Spark MOSFET unit is ok – it provides a nice smooth and stable output.
      However, from a technical standpoint, it does not address the issue of your stator burning out when your target charge is met – because it is still a short-type reg/rec.
      Whilst they are marketing it as running “much cooler” they are not reporting on how much cooler the stator is ‘versus’ the PODtronics.
      That is probably because it is no different!
      My advice? If your PODtronics ain’t broke, leave it exactly where it is!


      Yes indeed – both the warning light assimilator and the ignition switch are different on Canadian models.

      On the Canadian bikes, the switch has Norton Part Number 06-6625
      The Lucas Part Number for this is LU30825
      This switches on the Pilot Light circuit (pilot light, tachometer and speedo backlighting and tail light) when the key is in the “Ignition” Position.
      This switch was modified by Lucas for Norton, and was only used on the MK3 Commandos bound for the Canadian market.

      They had originally planned on offering a kit for the Rest of World bikes to improve the safety and your chances of being seen (as all the wiring was there already, and it would have been a simple case of just swapping the switch and headlamp warning unit) however, to my knowledge this kit never materialised.

      Because the switch was made especially for this bike, for what was a very small market, you cannot get replacements now (Wassell doesn’t make them)
      So if you fit the available switch (Lucas Part Number LU30552) you will lose the Pilot Light circuit being on in the “Ignition” position – that circuit will only come on with your key in “Position 4” – the same as the Rest of World.

      With the Canadian warning light assimilator (which they called the Headlamp Warning Unit) there is an addition of lighting up the headlamp, when the unit detects an AC output from the alternator stator (i.e., when the engine is running)
      You have taken this off your bike, so you don’t get that functionality – you will have to turn your Headlamp on with the On/Off switch on the right side handlebar switch.


      For Battery Status Monitors, I use the “Standard CWLs that power your choice of incandescent bulb or LED” from Improving Classic Motorcycles.
      The standard version allows you to connect the original warning lamp, so it blends in nicely on the MK3 dashboard.
      I haven’t found another one yet that let’s you do this, and I have fitted several to different bikes with no issue at all.
      Graham Blighe also has a store on eBay, which makes it easier to buy from him.

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