Problème électrique

M

Mick66

Joined
May 11, 2026
Messages
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Bonjour nouveau sur le forum j aide un ami qui refait un commando 750 fastback de 1972
Nous avons changé le faisceau par un neuf ainsi que le ballast qui était manquante , après avoir pu retrouver les correspondances des fils pour les feux les clignotants ect ,je n'ais pas d'étincelles au bougie
Quelle qu un aurait une idée de où chercher ?
 
"Hello, I'm new to the forum. I'm helping a friend restore a 1972 Commando 750 Fastback. We replaced the wiring harness with a new one, as well as the ballast which was missing. After figuring out the wiring for the lights, turn signals, etc., I'm not getting any spark at the spark plugs. Does anyone have any idea where to look?"
Click to expand...
Google translation.

But was the ballast missing for a reason? Has electronic ignition been fitted as that doesn't use the ballast resistor.

Electric for the ignition is white that goes to the handebar kill button then white/yellow to the under tank connection where it changes to white/blue which goes to the ballast resistor (for original points ignition only) then white/purple to both coil negative terminals then black/yellow and black/white to each set of points and one capacitor for each. If it has electronic ignition, which type or points please say which.
 
More info please .
Personally I eliminate the Kill switch by opening it up and soldering / crimping the connecions together , permanently . You have enough issues getting the vehicle started anyways , right ?
 
Problème électrique

Problème électrique

La moto est d'origine d ou la ba llast,nous avons changé le faisceau voilà les schémas fournis avec
le soucis c'est que sur le faisceau d'origine il y avait une branche en plus qui allait sur les commodo et sur le nouveau pas
Nous avons donc branché les commodos entre le 1er et le 2eme faisceau du coup j ai les feux les clignotants mais le coupe circuit n' est pas branché ou je ne c est pas sur quelle fil le mettre
 
The motorcycle is original where the ballast, we changed the harness here are the diagrams supplied with
the problem is that on the original harness there was an extra branch which went to the commodos and to the new step
Click to expand...
Translated by Google.

Sorry something must be getting lost in the translation as I don't understand what "an extra branch which went to the commodos and the new step" means?

but the circuit breaker is not connected or I don't know which wire to put it on
Click to expand...
Translated by Google.

What do you mean by circuit breaker? Do you mean the ignition switch or something else?

Can anyone who speaks French make more sense of this? Or anyone at all?
 
Here's ChatGPT's attempt :
"The motorcycle is original except for the ballast. We changed the wiring harness; here are the diagrams that came with it.

The problem is that on the original wiring harness there was an extra branch that went to the handlebar controls, but on the new one there isn’t.

So we connected the handlebar controls between the first and second harnesses. As a result, I have the lights and turn signals working, but the kill switch isn’t connected, or I don’t know which wire to connect it to."

Generally, the AI stuff does a far better translation than Google does. However, I don't use a standard harness on my bike, so I can't really help other than by offering a better translation.
 
SteveBorland said:
The problem is that on the original wiring harness there was an extra branch that went to the handlebar controls, but on the new one there isn’t.
Click to expand...
What extra branch to the handlebar controls, there isn't any that I'm aware of, all the handlebar wires are in the switch cluster harnesses, this sounds like some kind of owner modification? As I said previously the white/yellow (WY) is the feed from the kill button.
The wires you should have are here, there are no missing wires to the switch clusters.
Problème électrique
 
Mick66 said:
Je vais aller voir la moto la semaine prochaine et je posterai des photos des branchements
Click to expand...
Pourquoi ne pas participer aux discussions de ce forum en anglais ? C’est un forum anglophone.

Ainsi, personne n’aura besoin de traduire vos messages.

Cordialement
 
It could be that one of the switch cluster wires is faulty and a previous owner fitted an extra wire to replace it.

One switch cluster should have a white/red (WR) wire that doesn't connect to anything.
 
Torontonian said:
More info please .
Personally I eliminate the Kill switch by opening it up and soldering / crimping the connecions together , permanently . You have enough issues getting the vehicle started anyways , right ?
Click to expand...
If you wanted to eliminate the kill switch but allow for possible future reinstatement, could you remove the white wire that feeds one side of the kill switch from where it connects to the main loom under the tank, and also remove the white/yellow wire that feeds the other side of the kill switch from where it connects to the loom under the tank and then connect the two points that those wires were removed from with a jumper to restore the circuit.
 
This is exactly what I did .
After soldering together the 2 wires inside the switch I later on said " Why not just do it closer to source , under the tank at the harness ." Simplicity .
 
Note that the factory reversed the switch clusters during 1972 so they may be fitted opposite to what is shown on the wiring diagram.

One cluster should have;
White (W)
White/red (WR)
White/yellow (WY)
Light green/brown (LG/N)
Green/red (GR)
Green/white (GW)

The other cluster should have;
White (W)
Purple/black (PB)
Blue (U)
Blue/white (UW)
Blue/red (UR)

Normally there should be no other wires.
 
So using deepl

La moto est d'origine d ou la ba llast,nous avons changé le faisceau voilà les schémas fournis avec
le soucis c'est que sur le faisceau d'origine il y avait une branche en plus qui allait sur les commodo et sur le nouveau pas
Nous avons donc branché les commodos entre le 1er et le 2eme faisceau du coup j ai les feux les clignotants mais le coupe circuit n' est pas branché ou je ne c est pas sur quelle fil le mettre
translates to
The bike is original, including the ballast; we’ve changed the wiring harness – here are the diagrams that came with it.
The problem is that on the original wiring harness there was an extra branch leading to the switchgear, but on the new one there isn’t
So we connected the switches between the first and second wiring harnesses, so now I have the lights and indicators working, but the circuit breaker isn’t connected – or I’m not sure which wire to connect it to. So we connected the switches between the first and second wiring harnesses, and now I’ve got the lights and indicators working, but the circuit breaker isn’t connected – or I’m not sure which wire to connect it to.
 

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