Let’s talk about Tri-Spark

Grant Tiller

I am a huge fan of Tri-Spark, and have fitted a few of them with great results!

However, I think they are given a hard time in the groups and forums for their reliability.


It’s true – there was an issue a good few years ago with one of the components (I believe it was manufactured by Honeywell) that was not able to withstand the environment it was operating in.

Running everything inside the points cover means that high temperature and high vibration is more of an issue compared to the more common practice of running a simply pickup in the points cover, and having everything else in a separate control box.

However, this Honeywell part didn’t live up to the manufacturers own specs, so the failure was hardly the fault of Tri-Spark.

Stephen Kelly (the owner at Tri-Spark) worked with bike owners that experienced failures to make sure they were either reimbursed or given a replacement unit.

These problematic units look different to the ones you buy today – they have an anodised front cover, and no test button on the front. So they are easy to spot!

Grant Tiller


I think the other thing that needs to be considered, but is often overlooked is the wiring.

With everything packed into one unit, it is essential that the wiring to this is sound and reliable.

A lot of people will be reusing the BY (black/yellow) and BW (black/white) cables that used to go from the points up to the condensers, so it is essential to make sure the cables are in good condition and are not damaged or chafed in any way.

It’s a good idea to renew the rubber grommet that goes through the engine case – many people don’t know there should be one, as it is often missing. This will also help stop water ingress from the outside world into the points cavity.


The other point I think is worth consideration is the Positive connection.

The Tri-Spark is, as standard supplied with a ring connector on the red cable, which should be screwed under the 2BA standoff for the points cover.

Contrary to Tri-Spark’s recommendations, I personally don’t think this is a good idea.

Think about the route back to the Positive terminal on your battery:

Assuming you have correctly secured your red cable to the engine side of the head steady, and not the frame side, there is still a complex and dirty route ahead for the power to travel:

  • bolts covered in Loctite and thread lubricant
  • paper gaskets (base gasket and timing cover gasket) covered in Wellseal
  • head gasket, which may not be conductive if it is a composite one
  • plates that are painted or powder coated

If you haven’t moved your red cable from the frame side of the head steady to the engine side of the head steady, you also have isolastics to get through as well! These are a great electrical insulator as well as a vibration isolator!!!

Of course, if you are running a MK3 Commando, or a bike with an aftermarket electric starter kit, none of this should be an issue, because you should have a very heavy gauge cable running from the crankcase (right next to the starter) directly back to the battery positive terminal.

With all this in mind, I feel it is a great idea to run the red positive cable of the Tri-Spark directly up to the coils, instead of relying on getting it through the engine casing.

As an example, on our bikes I extend all three cables with soldered and heat-shrinked joints that are wrapped in cloth tape – so all three cables run together up to the coils.

I would LOVE to see Tri-Spark ship their electronic ignitions with three cables long enough to reach up to the coil under the tank (or back to under the seat, in the case of some bikes)

This would negate so many issues for their customers, and provide a much more robust and reliable system for a very low additional cost.

Grant Tiller

It’s quick and easy to do, and will rule a massive variable out from troubleshooting in the future.

After all, if you were running an electronic ignition unit with a seperate control box, it would probably live under the fuel tank, and tap into the red in exactly the same way.

I feel this is so important, that I have gone back through all the existing wiring diagrams I have posted on this site, and altered each drawing that contains a Tri-Spark electronic ignition to show the red cable going back to the coil.

Here is an example of what I mean:

Grant Tiller


The other point to think about is RFI (radio frequency interference) and EMI (electro-magnetic interference)

It was found that certain PODtronics regulator/rectifier units are known to cause issues with Tri-Spark ignitions.

Tri-Spark used to be a reseller of PODtronics regulator/rectifiers and found that some of their units caused a misfire at between 3,000rpm and 4,000rpm.

You can read the Tri-Spark technical article about this topic by click here:

Grant Tiller

Tri-Spark have recognised the issue and have made a choke/filter available for purchase that will address this problem for those that are experiencing a misfire/flatspot.

Grant Tiller

You should note that this is a PODtronics issue – their circuitry is producing a dirty/noisy supply.

The above filter/choke is connected to the reg/rec.

Grant Tiller

To my knowledge, Tri-Spark have not been able to replicate this issue with any other reg/rec.

There have been very many PODtronics regulator/rectifiers produced over many years and the design/components used have been tweaked, changed and optimized – if you are unsure what model you have, and whether it is an issue, I would suggest you reach out to Stephen Kelly (the owner at Tri-Spark) and check with him.

Hopefully someone, somewhere will find this article useful.

I have several Tri-Sparks, have them wired up properly and I have not seen any reliability issues.

I don’t think I am lucky – these are good systems.

11 replies

  1. “You should note that this is a Podtronics issue – their circuitry is producing a dirty/noisy supply.” This is only when the Tri-Spark is used with the original unit designed by Bob Kizer before electonic ignitions were widely used. It was designed to replace the Zener and Lucas rectifier when point systems were the norm. That is nearly 50 years ago now. There are still these units being used today where the motorcycle’s electrical system remains balanced and are showing no signs of premature aging. You should also note that it is only the TriSpark that experiences this problem and it seems to be exasterbated by the use of Lithium Ion batteries. The latest iteration of the Podtronics unit address the problem with TriSpark being 200 plus watts with the output filtered. There is also a web site showing a Podtronics unit deawing .5 miliamps. This site is degenerous at best. A unit out of the box draws less than .1 miliamp and yes with age, heat and abuse overtime can degrade. Even at a .5 mili amp draw he admited it would take a year to drain a fully charged battery. This would be the same for an abused Mosfet unit (they do degreade, just normally not as fast) which is also a shunt regulator (or as you want to call it a “short’ regulator – as is a Zener). The only ones that are not are series – or open – regulators and they are beyond what the market can support.

    • Hi John, and thanks for reaching out.

      I am sorry that you don’t like what you are reading, and that you feel my website is “degenerous at best”

      To your point about parasitic drain – you seem to mis-understand the point I was making in the article.

      I am saying that I don’t think that ½ milliamp drain is a problem.

      This article was written in response to someone that was implementing a relay into his ignition circuit to make sure there was no parasitic drain when his ignition switch was off – an action that I felt strongly was not necessary and could potentially introduce more issues than he is fixing.

      In the article, and in support of your PODtronics product, I pointed out that I felt it was a non-issue, and I drew comparison to a car, that would behave in exactly the same way.

      Regarding my Tri-Spark article – I was pointing out areas that have given Tri-Spark a bad reputation, and addressing points that people have raised on the forums and groups.

      There is an issue of a flat spot between 3,000rpm and 4,000rpm on the Tri-Spark classic twin, and it has been attributed by the manufacturers to a problem that only manifests with a PODtronics reg/rec.

      Tri-Spark used to sell PODtronics, so I assume they know plenty about this.

      I felt it was good to add details to this article, point the reader to the Tri-Spark website, and the informational pdf they have written.

      I was pleased to hear that you are developing a MOSFET reg/rec – your PODtronics product still has the strongest brand in the market, so there is a decent opportunity for you there.

      I disagree with your point about an open-type unit being commercially beyond what the market can support.

      There are many people looking for an open-type MOSFET reg/rec, as this would be the ideal solution – utopia if you will.

      Putting another short-type MOSFET reg/rec out into the market doesn’t address the issue, it is merely pulling market share from the smaller companies that are doing that already by leveraging the strong PODtronics brand.

      Why not be responsible and innovative by putting out a technically smart solution – brit bike owners love you John, as you are one of the nicest guys in the industry – you’d be well supported for doing the right thing!

  2. Hi Grant,

    I had an interesting issue last fall when I fitted a Trispark to my bike, previously fitted with a 200W Podtronic and an Alton Electric Start. My bike of course spontaneously developed the well known phenomena, so I sourced the Trispark filter and fitted it per your diagram above. The miss fire went away, but then so did my charging system!!

    Tried everything to make it work, but my bike wasn’t having it. In the end, I removed the Podtronic, and went back to a rectifier and Zener diode. Ironically, the alternator performance is much improved without the Podtronic – better top end voltage and much faster battery recovery time after starting. My Alton alternator will not exactly set the world on fire with power, so it needs all the help it can get.



    • I really like the zener – it’s a great solution!

      Both electrically and mechanically connected to the bike.
      Mounted on a nice lump of cast aluminium stuck out in good airflow, it’s a great way to scrub off excess power as it’s heat sinking capabilities are hard to match!

      And they are actually very robust too – they just need to be cared for.
      They usually ‘fail’ when they are not looked after, allowed to get wet and corrosion sets in.
      It is important that both contacts are kept clean, and the cable connections are good.
      Doing this means there is nothing to stop them from operating efficiently for another 50 years!

      The rectifiers are the weak part of the charging system, as the soldered diodes between the cooling wafer fins are susceptible to dry joints.
      Many people will be riding around with a diode down, which basically gives you a half wave rectifier instead of a full wave one, and a choppy, lumpy output.

      …I think that’s where their poor reputation probably came from.

      The rectifier of course can be replaced with a modern equivalent – which is much more robust, as it is potted in resin.
      These are sold in every electronics store, and only cost around 5 bucks!

      The Alton stator is OK – more or less equivalent to the original RM21.

      It’s a tough ask to charge a depleted battery with it during a ride, but in all honesty that’s actually a good thing… think about it – you are not producing more power than you need, so there is no need to scrub it off with a regulator!

      …Lucas had the right idea originally – put back what you take out and nothing more 🙂

  3. I agree – simple but elegant.

    I am running a modern potted rectifier, plugs straight into the old harness.

    I switched everything to over to LED’s for lighting (and I mean every thing – LOL), and the Alton keeps up just fine. Definitely seems to be quite balanced to my loads.

    The only issue I had with the Alton Stator is one of the solid core leads fatigues and snapped off. I mechanically attached a piece of multi-strand wire to the stump, then soldered the joint and put a bit of heat shrink over it. I then supported the stator wires off of the primary cover boss to limit vibration. It has been over a year and it is still holding (knock on wood).

  4. Hi, i installed a trispark that had the A B positions for clockwise and counter clockwise. Great results.
    I have just purchased another unit for a similar bike, the new unit has AC in what was the A position and CW in what was the old B posion. If you assume AC is for anti clockwice and CW is for clockwise, then they have reversed the positions. I am confused?

    • Hi Graeme,

      Tri-Spark used to have two models:

        TRI-0005A – this was for clockwise installation (Atlas and Early Commando with the points behind the engine)
        TRI-0005C – this was for counter-clockwise installation (Commando from 69 onwards)

      The units were not interchangeable, so Tri-Spark resellers had to carry twice as much inventory.

      Towards the end of last year (2022) they introduced an updated unit TRI-0006 – which is capable of working on BOTH clockwise and anti-clockwise timed bikes.

      The units are marked up slightly differently to the older model:

        CW – clockwise (Atlas and Early Commando with the points behind the engine)
        AW – anticlockwise (Commando from 69 onwards

      Graeme, you are absolutely right with your observation – between the old unit, and the newly updated one, the marks for clockwise and anti-clockwise have indeed been swapped over!
      Fine for people that are new to Tri-Spark, as they know no different, but a point of confusion for people like you and me that have them fitted to other bikes!

      I know this has already caught a couple of people out, and I am surprised that Tri-Spark have not made a point of calling it it more clearly in their instructions.

  5. Hi Grant , The cheap potted rectifiers are indeed a wonderfull replacement , I do think it should be made clearer that they need to be cooled. I melted a couple before I woke up fitted a heat sink .

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