power abuser = cct/voltage stabilizer
cdi = Capacitive Discharge Ingition (CDI) Operation.
The CDI itself is really just an amplifying switch with time delay. It sits there storing up electricity in a capacitor (ie the "C" in "CDI"), then the pulse sensor spikes the input, the CDI waits a small amount of time and then puts the burst of electiricity it stored into the coil. That small amount of time represents the advance curve of an engine, ie at idle an engine may need 10 degrees advance but at full revs it may need 40 degrees advance. By delaying the signal and having the pulse sensor in the right place, the CDI can make sure the engine is getting the right advance curve.
Rounding it off, the CDI is connected to ground (so that electricity can flow) and an Engine Kill Switch will short out the CDI resulting in no spark and thus the engine will stop.