in simple Term From the Spark Plug Removable end(cover), To A Lock Off Switch (flick On Switch)To the Bike's Engine body  Or Frame..
So when current passes throw the sparkplug head It Uses The FasterWay Of hitting Ground (Frame) But this time it will be Going thow the switch When the circuit Is Compleate..No Spark & No Source Of it Lighting In the engine Very Simple
                
 Try this
                
 January 2008