Firstly, I apologise for being a pedantic prick!
"the same impedance (measured in ohms with multimeter) .."
"the coil impedance (resistence) "
Although impedance is measured in ohms, you can't measure the impedance of a coil with a multimeter, you can however measure the resistance, which will be a lower value than the impedance of the coil. The impedance (the total opposition to current flow) is the result of both resistance and reactance. In the case of an ignition coil, the reactance would primarily be "Inductive Reactance". Futher explanation would be to painfull to inflict upon you.
Re: 4 stroke V's 2 stroke coils, there "could" be some difference in the duty cycles for coils used on points ignitions as a 4 stroke only has to charge/discharge the coil every 2nd revolution as opposed to a 2 stroke, which has to charge/dischare the coil every revolution, however I doubt that they would bother, and the makers of the coils would just make the coils to the higher duty cycle. As a lot of 4 stroke engines with electronic ignitions fire a 'wasted spark" on the exhaust stroke, I would doubt that there would be a difference between a 4 stroke and 2 stroke coil.
Many magneto points systems do not operate on 6 or 12 volts as found with battery coil ignitions. Generally speaking if a magneto/points ignition system is quoted as being a 12V system, this is only a nominal voltage, and the voltage can rise significantly higher as the engine rpm rises.
Also be aware that many electronic ignitions operate a voltage significantly higher than 12V, most are in the order of 40 - 80V, however some do operate at voltages up to 400v.
Again, I apologise for being a pedantic prick!
CJ
