Complete new electrical system - Commando 750

Go modern. Voltage control  - Al O does a reliable control unit for a single phase system. Way better than old zeners.

Consider a potted double output coil to provide the sparks, unless you want the colis dangling from under the tank look.

Regards, George. 

Is Alan Osborn, aka the clubs electrickery expert and runner of AO services in Thetford.

You might need to buy new coils, as the originals for points ignition would have been 12V ones but for the Boyer you will need 2×6V coils wired in series. 

Regards, George 

The original stators where quite good, so no need to replace before it proves faulty when bike is running. The rotor might have have weaker magnets, ride testing will tell. I think too many fits high output or three phase alternators. Maybe they spend most of their time idling with lights on. Or have fitted heated grips or tea kettles. As already said, a rectifier/regulator from Al O is a good upgrade that replaces the rectifier and the zener. If you go this way a 5 Ah battery will do. Of course a bigger and heavier battery can be used. I've found the battery status monitor more useful than an ammeter. Also from Al O. I've found an upgrade to H4 headlight gives better light. A well working charge system don't need LEDs fitted. Only makes more of alternator output turned into heat. But LEDS can withstand vibrations better.

At the very least, I suggest, an LED brake/tail light, to discourage car drivers from tail-ending you. Paul Goff (http://www.norbsa02.freeuk.com) has versions with red LEDs for the brake/tail function, and white ones to illuminate the registration plate.

Personally I would go for an LED headlamp too. Goff's Daylighter 2 is a 5000 lumen H4 bulb that's rated at 30W — I'm very happy with mine.

Just a thought - as you're starting virtually from scratch and if you're feeling adventurous, you might consider converting to negative earth - it will certainly make fitting any modern upgrades etc. easier. The wiring loom will be fine as-is. There's an article in next month's Roadholder about it.

If I'm wrong,  I am more than happy to be corrected. I didn't think the Commando used wasted spark with the points set-up. Did Norton use a ballast resistor with the coils then? Trying to improve my knowledge base here.

Regards, George. 

later Commandos 71 onwards? used two 6 volt coils in parallel with ballast resistors so they worked in a 12 v system, fired sequentially. Most modern EI's use those 2 6v coils in series, no ballast resistors and wasted spark.

Some good and some poor info here. George F- Nortons NEVER used wasted spark. The coils on early Commando were 12V while later they were 2X 6V with one ballast resistor, this is NOT a parallel circuit. This idea had two reasons, A) a low battery voltage would start better with 2X6 as the percentage drop on the coil was lower, B) electric start was a glimmer in the designers eye. There is nothing wrong with a good zener diode, we have had them for over 50yrs! The problems with zeners is this-A) with age they tend to drift high in voltage ie too much for the 12V battery. B) you can't buy them. There is a chinese version, maybe from USA but I do not trust it as I have not seen its specification. (nor tested it) Michael R-your info on alternators is good. Wiring negative earth-why? perhaps you want to have a built in sat nav, or video system! The loom will not be good enough as the earth wires will all be RED they need to be BLACK for negative earth. 

Paul Caracary- please phone, I can supply coils, regulator and wiring.  aoservices.co.uk

I also have a 1970 Commando. Also got it as a basket case with some parts missing. I use the  new  "LUCAS" replica  wiring harness and an electronic voltage regulator. No Zener diode or rectifier.Ignition is a Boyer box with two (new) 6 volt coils. Rear bulb is LED and also the instrument bulbs are from http://www.dynamoregulatorconversions.com/.  The sell negative earth LED bulbs.

Once on a ride in the evening with lights on I barely made it home. Bike was running mainly on battery power and the engine stopped when approaching  red traffic lights. So I bought the high output two phase stator from NOC spares. No problems since with the voltage.