Help identifying ignition settup, '72 750 Commando

Manu

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Feb 2026

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28

• Wednesday at 12:59 PM

• #1

Hi - I'm trying to understand my existing ignition before dismantling to install TriSpark ignition along with CNW coil. Bike has Boyer and 6V coils but wiring does not seem to match the OldBritts diagram I found in resources. Coils have more connections than the diagram and the Boyer unit has 4 instead of the 5 wires shown in the diagram. Was hoping someone could explain what setup I have. Pictures attached (I hope).
Thanks - Paul

 

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L.A.B.

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• Wednesday at 1:36 PM

• #2

The item in the first picture is a Tympanium Reg/Rec unit. The Boyer box I can't see it.

 

Manu

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• Wednesday at 2:16 PM

• #3

Thanks. I cant see any markings on that and the Boyer sticker was next to it. Confused me (easily done).

Found the Boyer. Was under frame with padding glued to it.

Sure seems like lots of connections to the coils.

 

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1973x75

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• Wednesday at 2:27 PM

• #4

I’ve had my Boyer MK 3 with the original coils for over three decades, and I replaced my bulky Mighty Max with a Tympanium about five years ago, and the system has been very reliable.

 

L.A.B.

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• Wednesday at 2:28 PM

• #5

MkIII https://www.boyerbransden.com/pdf/KIT00053.pdf
MkIV and Mk III wire the same so I don't know what any possible extra wires are for.

 

Manu

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• Yesterday at 12:10 AM

• #6

Thanks for your patience.

Am I correct that this is a Lucas 2MC capacitor?

 

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dobba99

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• Yesterday at 12:26 AM

• #7

Manu said:

Thanks for your patience.

Am I correct that this is a Lucas 2MC capacitor?

Click to expand...

No, that is the warning light assimalator

 

L.A.B.

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• Yesterday at 1:57 AM

• #8

The 2MC if there should normally be in the battery comparmtent and is usually blue. When in doubt check the wire colours/colors.

 

Manu

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• Yesterday at 10:53 AM

• #9

Is there a full schematic set for the '72 750 somewhere. I haven't found one in resources. Only the Oldbritts simplified.
Thanks

 

L.A.B.

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• Yesterday at 12:04 PM

• #10

https://www.classicbike.biz/Norton/Repair/70up_Commando/70upCommando.pdf

There's a wiring diagram in the electrical section.

 

Manu

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• Yesterday at 3:01 PM

• #11

Ahh. thank you