primary and secondary windings of an ignition coil.
Of particular interest is the 6VAC breaker-point ignition
circuit common to older Japanese motorcycles, where an
A/C generator consisting of a stator and flywheel produces
6VAC output for the primary windings of the ignition coil.
Results from testing resistance for a selection of used coils
and one new coil (for a similar but different model series)
revealed some discrepancies, but not enough is known to
determine whether they are significant or trivial. This testing
also stirred curiosity about the ignition performance consequences
arising from the practice of adding resistance to the secondary
side as a means of inhibiting broadcast signal interference.
** === About the ignition coils ======================= **
A Service Manual gives values of 4-5 kΩ for the secondary
coil winding. No value is offered for the primary winding, but 1 Ω
Three used coils for the model tested at 8 kΩ and 0.7 Ω. Another
tested at 8.54 kΩ and 1.7 Ω. A new 6VAC coil from the same mfr,
but for a different model, tested at 5.4 kΩ and 1.4 Ω
Used Resistance Spark Plug caps tested at 5.81 kΩ. (One example
was fitted with a non-resistance cap that tested 0 Ω.) A new
cap tested at 4.77 kΩ.
** === The questions: ============================== **
- All other things equal, what would the consequence of
increasing resistance on the coil primary side from 0.7 Ω
to 1.4 Ω and 1.7 Ω be on the intensity of energy across the
electrodes of a spark plug.
- Does an increase from 0.7 Ω to 1.4 Ω and 1.7 Ω on the
coil primary present a possibility of coil input requirements
exceeding output of the existing 6VAC generator.
- All other things equal, what would the consequence
of increasing internal resistance on the coil secondary side
from 4-5 kΩ to 8 kΩ and to 11 kΩ be on the intensity of energy
across the electrodes of a spark plug.
- Is there any difference between increasing secondary
resistance internally at the windings versus externally
by way of introducing resistance in the spark plug cap
and or in the spark plug?