Chassis electrical system

[sllawo]

Hi CrazyCarl on first I want tell you my English is not very good but I try
my best. I have china motor bike Skyjet SJ125GY-3A it's 125cc 4-stoke engine
with CDI Ignition. And No I have problem because I take out cables from CDI
and I don't know how to put the cables in order e.g. black-red go to the left
top. I need instruction how to find. i looking that 2 month :( and I'm tired
. Please help me








I need some information and sorry for my English ....

[CrazyCarl]

Sllawo...

When you have some time and energy, can you post the pictures and describe how the problem first started?

CC

[sllawo]

Exactly I need to know in which way I must to put cables in CDI UNIT. I want pictures from the another china bike with the cables because i dont want to burn next CDI

[forchetto]

I've got this image of a similar CDI unit's wiring. Does it help?:

By the way, the wire shown marked "restrictor" could be coloured Grey with a White trace. I think the red shown is for clarity. This wire (if fitted) is reckoned to be the magic wire that when removed "de-restricts" the engine. I believe all it does is to remove the RPM limiter enabling the engine to rev higher.

[sllawo]

Yeah it's ok but can you tell me what voltage is in each cable because colours ale difference but voltage not.


PS. from which bike is this CDI?

[forchetto]

I think it's from a Skyteam ST125, but the colours tend to be standard.

Difficult to tell the voltages, as this type of ignition system works only from the magneto and has no need of the battery, so when the engine is off there should not be any voltages around anywhere.

The black and red wire comes from the high voltage winding of the magneto. This high voltage (150 volts or more) is only present when the magneto is turning and it's used to charge a capacitor inside the CDI unit (CDI= Capacitor Discharge Ignition).

The blue and yellow comes from the pulser, sensor or pick-up coil. This is a magnetic sensor fitted next to the magneto rotor. The rotor has a small magnet that as it flies by this sensor coil generates a pulse of a few volts, sufficient to trigger the gate of a thyristor that discharges the capacitor through the ignition coil primary windings. This induces a very high voltage (15000 Volts +) in the secondary winding to produce the spark at the plug.

The black and white usually goes to the kill switch, this being a button on the handlebars that shunts the magneto output to earth, so killing the spark and stopping the engine. On some bikes this could also be linked to the safety switch on the side stand that prevents riding with it down.

The black and yellow takes the high voltage from the capacitor discharge to the primary of the ignition coil and through it to earth.

The green is earth and should be connected to the chassis.

The one marked "restrictor" coloured Grey and white (??) seems to be part of an RPM limiter to stop you over-reving the engine. It may be set at lower than ideal revs to limit the performance to comply with regulations limiting top speeds or power outputs.
Some say that removing it improves performance, but I couldn't say.

[sllawo]

Thank you thank you Tomorrow I try :)

[CrazyCarl]

Sllawo,

Definitely keep us posted on your progress and good luck!

That sure looks like A LOT of wires!!!

CC

[sllawo]

OK I find next problem... On magneto is cable and was burn/drowned look on this picture...



And why magneto is in oil? First time in my Live I see wet magneto.... maybe some one explain me why ...

And few more picturesif someone want to see
That cables go from magneto:




And My CDI. I put in this way cables:

[forchetto]

The black thing is the high tension coil of the magneto. You can tell because it is bigger than the rest, having a much greater number of turns of a finer section copper wire.
Not sure if it's burned or the insulation tape was that colour to begin with. It's not normal for it to burn out as it doesn't provide a lot of current, just a high voltage.

Magnetos on that bike and many others run in oil. Sometimes on Honda Cub derived engines they run dry, but it's quite normal to run them in oil. Can't understand why...