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July 8, 2019

Norton Commando Wiring Diagram + Tri-Spark

by Grant Tiller
Grant Tiller

The new kid on the block for Electronic Ignitions is Tri-Spark.

Well, I say new kid – they have been around since about 2009.

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 point 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.
  • Black/Yellow – this is the negative feed to the Tri-Spark unit. This joins in to the White/Blue wire that used to feed the Ballast Resistor that you are removing. As standard, this goes up to the big connector block under the tank, where it’s joined to the White/Yellow that is the kill switch on your left side handlebar switch cluster.
  • Black/White – this is the negative supply FROM the Tri-Spark TO the coils.

As with the Boyer, from a wiring perspective, the most important thing to note is that you will be moving from a pair of coils that are wired in parallel to series.

Originally, the points make and break the positive (earth) side of each coil in turn.

The Tri-Spark electronic ignition system uses a concept called “wasted spark” – with the two coils wired in series, they are energized together on every rotation of the camshaft.

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. circuity 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)

Good Quality JPG 1280×769

Grant Tiller

High Quality PNG 3066×1841

Grant Tiller

In the very early days of Tri-Spark, a few people reported Early Life Failures – i think due to over heating.

However, there have been a few minor revisions along the way, and these units are now proving to be superbly reliable.

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