I've got this over the internet by some guy and below is the link to his article. Correct me if i got it wrong but somehow i understand it works that way. Because the 125 SM/SX has it installed by default and i guess the additional accessories is for the ppl who want something more than the "CONTRACT FREE CAPACITOR IGNITION (CDI)" Which i dunno the difference.. hehehehehehheh
Oh ya if someone can highlight to me the difference or the advantage of the accessory i might want to chg mine myself.. http//www.users.bigpond.com/jack_stands/automotive_advice/ignition_system/ignition_2.html
CDI ( Capacitor Discharge ignition )
The thing has a whole bank of capacitors and is electronically controlled it delivers a big Charge at the coil secondary and the switching is triggered by a magnet on the rotor and the Coil charged by an inner charge coil on the crank rotor it does not need a battery great for Motocross and Road racing. where weight is a premium factor. On some road trail bikes there is another charge coil for the head light too and it bleeds a bit too a small battery to toot the horn or run the blinkers or tail lamp if fitted.
There are variations on this in bikes but the principle is the same (save a magneto ignition)
of which produces the secondary current from itself, very big, very dangerous to play with.
they only need half a crank to fire a bolt of power up your arm.
This is a popular trick in hot rod shops Hey hold this screwdriver here ill just turn the lever a little.
Hey don't roll on the floor you'll get dirty !
The next generation of ignition coils are not oil cooled and have a different configuration they are not centre wound coils instead the are wound on to an E shaped pole a much cooler and more powerful wind with less EMRadiation and line noise similarly as toroidal coils are like a doughnut and provide good performance in audio applications with low noise they are not just wound on to a post one inside the other.
This has many benefits for computer controlled ignition as it as a much more predictable and controllable coil remember the computer does not turn the coil on and off that is done by the module the computer just allows the crank angle sensor to operate the module and gets a reference signal from it too for engine speed so it can go and do the fuel stuff with the rest of the info it gathers the computer can also signal the module to set its advance curve so the computer will contain ignition mapping as well or on some fords this was done at a multi function module on the Distributor with engine speed read there you may have tested the P.I.P output of one before.
You will see this in schematic diagrams in tech manuals. Each system has its small functional differences to this so over the period of time I will post details and codes and tests for each of these systems I can get all the info on, and I've got a lot already.