pierodn wrote: I found on Commandos some Lucas coils both by 6V and other both by 12V.
My knowledge is that the electrical Commando system is 12V has the 6V coils placed in series (+-+-), while those from 12 V must could be put in parallel (++--).
It is so or 12V coils should not be used?.
6V or 12V coils are only wired in series when the original Commando points ignition has been replaced with a "wasted spark" electronic ignition system (the ballast resistor also has to be disconnected).
Both "2x 12V coil" and "2x 6V coil + ballast resistor" Commando ignition systems have coils wired in parallel
(compare the pre-'71 and '71-on wiring diagrams, both diagrams show the coils in parallel).
pierodn wrote:The electronic injection (Boyer/Pazon) can be used with both coils from 6V or 12V too?.
I have some confusion because I'm studying now the electrical wiring system of the BSA 1969 Rocket 3 and I understand that it has 3 x 12V coils in parallel (right?) but if you want to fit the electronic injection must replace them with 3 x 6V (in parallel = 6V!!!!) or (3 x 4V in series = 12V).
3x 6V coils in series will probably work well enough, but 3x 4V coils in series is to be preferred (3 x 4 = 12).
dave M wrote:I must admit I don't know why this was done, although it is common practice in automobiles to run a 6v or 9v coil with a ballast resistor which is bypassed while the starter circuit is engaged.
Therein lies the clue, as Norton did intend to fit an electric starter to the Commando for 1971, the same year the ignition system changed from two 12V coils to two ballast-fed 6V coils. The electric start 850 MkIII did make use of the ballast bypass system for starting (as did the electric start Triumph T160 which had 3x 6V coils with ballast resistor).