Ignition Control Module / CDI Question

[alff]

Can anyone tell me the difference between an "Ignition Control Module" and a CDI unit?

From my understanding, I have a coil which turns the 12v from my battery into lots of volts then the ignition control module controls when these are released to the plug to make it spark and ignite the fuel/air... Is that complete/correct or did I miss a step?

I'm talking about on bikes without magnetos.

Many thanks.

[Lutin]

"Ignition Control Module" and "CDI" are just different names for the same function - that of ignition control. (CDI is a contraction of Capacitive Discharge Ignition, by the way)

Yes, you are correct in that the coil "converts" the 12 Volts into lots of volts to feed to the spark plugs. However, any switching or control is always* carried out on the low voltage side (12 Volt side). This is carried out by the ignition control unit that handles the ignition advance curve.






* Stands to be corrected

[alff]

Thanks.

Bloody confusing things. I think I pretty much have it simplified down now though. When I press the electric start the ignition coil changes the volts from 12 to many thousands, the ignition control module controls their timing so the spark plugs fire at the right time. Igniting the mixture, starting the engine. Then when the engine is running the ignition coil continues changing the 12 volts into thousands, ignition control module releases them at the correct time, engine keeps running.

Unconnected to that the stator is generating power, rectifier converts it, power feeds the battery, battery feeds the ignition coil. Cycle continues.

Is that correct or is the process different when the engine is first starting?

Thanks again.

[Lutin]

Thanks.

Bloody confusing things. I think I pretty much have it simplified down now though. When I press the electric start the ignition coil changes the volts from 12 to many thousands, the ignition control module controls their timing so the spark plugs fire at the right time. Igniting the mixture, starting the engine. Then when the engine is running the ignition coil continues changing the 12 volts into thousands, ignition control module releases them at the correct time, engine keeps running.

Unconnected to that the stator is generating power, rectifier converts it, power feeds the battery, battery feeds the ignition coil. Cycle continues.

Is that correct or is the process different when the engine is first starting?

Thanks again.

That's just about it.