I can’t see the logic in using this system on a Commando, or any other side points/alternator engine (so most engines after the early 60’s).
These all use readily replaceable/upgradeable alternators and charging components, and also readily replaceable/upgradeable ignition components.
I think the potential market for systems like the Electrex is primarily on a pre-unit where the magneto requires reconditioning. Getting this done properly can be a considerable expense.
I myself baulked at this in 1981, and chose the Mistral Lucas
Rita magneto replacement option. This was about half the expense of a magneto recon at the time (and reading about magneto recons subsequently, I’m unsure that spending the money on the magneto would have been the best use of my scarce dosh).
It wasn’t important to me to retain the original magneto as my bike is a bitsa.
Problems after 30 years caused me to replace that setup with a magneto replacement body from Norvil (they are available from several sources) which allows the fitment of any of the common EI’s, or even contact breakers.
The additional ~40W load does require a decent alternator system, if you want to use lights. A high output RM24 system would sort it nicely.
As you don’t intend using lights, your original alternator will probably get by, but you will need to convert to 12V (cheap reg/rec, battery
I would do it properly, but it depends on your intentions with the bike.
As the Electrex system only supplies ~65Wmax at higher rpm, it can only hope to power a low wattage headlamp bulb (say 35W) with tail/ancilliary (say 10W) brightly at above ~3000rpm.
Even your original alternator (assuming the rotor still has reasonable magnetic strength) would give approaching 100W in a 12V system.
There were a few aspects of the review that I thought a little unfair to Electrex.
There must be many users running about with these systems by now, surely, accepting their power limitations, but running? I find it hard to believe that such things would be on the market for such a long time which didn’t perform their basic function.
Don’t get me wrong, this is not a system for a practical road bike, but for a road legal off-road bike, it could be the answer.
The spark is hard to observe because with CDI it is extremely brief (compared to conventional Kettering).
This feature can make CDI unsuitable for some engine combustion conditions, where a longer duration of spark gives a greater chance for an ignitable mixture to be near the electrodes.
I recall CDI being introduced big-time in the later 70’s Jap 2-strokes, as it broke through the fouling of plugs by oil.
CDI for 4-stroke engines has often included “multi-spark” which gives several sparks sequentially, in a way emulating the length of a conventional spark, especially at low starting rpm when the mixture is least atomised.
I have no idea if the Electrex system employs such technology, I am doubtful.
The HPI instructions do say:
“Do NOTextend cables, this may cause interference and damage to the CDI or the engine”
While I don’t think that any extension of charging cables will matter at all, the cables between ignition trigger and CDI, and CDI to coil may be more significant.
The cables from the alternator coil to the CDI then to the coil need to be carefully matched, and avoid proximity (not running anywhere near) to the generator wires.
According to the story, all these wires were considerably extended.
The author describes the pathetic illumination of the headlamp when running very rough. I can’t imagine (and hope) that wasn’t at any great rpm.
Without knowing the expected demand (ie the wattages of the bulbs), this doesn’t mean much at all).
Of course, not much can be expected of 65W maximum output.
Only the 5 Kohms of either the caps or plugs should be used, not both as the author experimented with.
“Note: don’t expect to see 12 volts on these (the coil has a primary side resistance of on 0.6 ohms, which is very very low, so my guess is it will only ever receive just a few volts from the CDI unit)”
The author doesn’t understand CDI, it is a high voltage, very brief pulse through a low resistance coil, but you won’t notice it with a meter, only an oscilloscope.
What are your requirements? Do you need to keep a magneto (in appearance)? Or do you want a working system regardless?