Powerdynamo, twincoil or 2 single coils?

Powerdynamo brings new ignition & light
to your vintage motorcycle



Technical Help



Customers often ask us whether a twin ignition coil in a system may be replaced by 2 singles and whether this might be better.

(except in Sports ystems with internal rotor) it is generally possible to replace a twin coil by 2 singles. 
  • the advantage of the twin coil is that the system gets cheaper and the assembly effort is reduced
  • the advantage of 2 single coils in parallel is that, should one spark plug fail, the other will not be affected (which in the twin coil it could be). also that on both spark plugs you have the same spark shape (negative spark) and you can easier regulate your carbs (should there be 2) for each cylinder,
Having said this, it has also to be said that we have many thousand engines running with twin coils without any negative effects.


In single coils one end of the secondary winding is earthed

In our (and other) twin coils, both exits lead to spark plugs and only via the plugs connect to ground.

The typical resistance between the exits is 6,2kOhm.

see our Information on the twin coil
remark on price: as the difference between a single and a twin coil is (besides the housing) only internal wiring of the secondary coil, both are about same price.

Verkabelung Ersatz der 9521 durch 2x 9522
  • weiß des Kabels vom Stator bzw Steuereinheit  (Masse) auf
    braun der Zündspule
  • rot (Ladespannung) auf rot
  • gelb des Stators bzw. blau/weiß des Kabels von der Steuereinheit
    auf gelb der Zündspule (Impuls)
  • es genügt eines der beiden blauen Ausschaltkabel zu nutzen
    das andere bleibt frei
Verkabelung Ersatz der 7238  durch 2x 1321
  • braun des Kabels vom Stator  (Masse) auf
    den metallischen Halter der 1321 (wichtig!)
  • rot (Ladespannung) auf rot
  • weiß des Stators auf weiß der Zündspule (Impuls)
    auf gelb der Zündspule
  • es genügt eines der beiden blauen Ausschaltkabel zu nutzen
    das andere bleibt frei

Should you install a twin coil or a second single coil aftermarket to a single/one plug engine, please note that  with this the amount of sparks increases, that is more energy is consumed which may lead - compared with the 1-plug situation - to worse starting (higher starting speed needed). Also experience tells us that after the change different ignition timing is needed - mostly less pre-ignition. How exactly to set timing than you will have to ask the mechanic who modified your engine. We would not know this.
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