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Ignition Coil Solution (without ballast if possible)

Discussion in 'Norton Commando Motorcycles (Classic)' started by thunderbolt, Jan 11, 2019.

  1. thunderbolt


    May 16, 2016
    Restoring my '74 Commando and will be fitting a Boyer electronic ign and would like to keep the dual coils to retain the original looks.

    I would like to keep the original coils (6v) and dispense with the ballast resistor to simplify the wiring when putting it back together. I could go to 2 x 12v coils to fit in original holders in place of the 6v coils.

    Advice on if I can remove the ballast resistor and what alterations would need to be done to have the different setup. The main thing I want to do is remove the ballast resistor and have a different setup that retains the same or similar shaped coils.

    Thanks Don
  2. comnoz

    comnoz VIP MEMBER

    Dec 10, 2008
    Two 6 volt coils can be connected in series and used with a Boyer.
    There will be no need for the ballast resistor.
  3. baz

    baz VIP MEMBER

    May 26, 2010
    Just keep your standard 6v coils they work best with a Boyer aswell
    If you are going to buy new coils and you don't like Lucas ones then PVL coils are meant to be good,
    And are the same physical size I believe
  4. thunderbolt


    May 16, 2016
    So can I just cut the wiring to the ballast away or do I need a wiring diagram?

    Or do I just follow the Boyer wiring diagram for the electronic ign?

    Thanks Don
  5. toppy


    Dec 2, 2012
    In the Boyer instructions it tells you what the resistance of the coils should be that the unit is designed to work with. If your existing coils are within that you should be ok or if you buy new 6v ones that is what you must check.
    The unit is made to work with standard coils but is more sensitive than points to using faulty ones or the wrong type but can be used with single 12v or double coils of 6v or 12v if resistance is in spec an fitting instructions are followed.
  6. MexicoMike


    Jan 31, 2010
    On my 850 I simply wired the coils, as Jim said, in series, disconnecting the ballast resistor completely. Ballast resistor is still there, just not in the circuit. I'm using a TriSpark but the series wiring of the coils if you are using the original types, is the same. There was no issue at all re coil resistance.

    The TriSpark (I assume the Boyer does the same) instructions showed the wiring if using the two original-type coils.

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