Ignition is provided by a sophisticated unit that is also common to many OS petrol engines. The main HT lead is shielded to prevent spurious emissions and the spark is delivered by a high quality CM-6 spark plug. Not quite a fit and forget system but pretty close!!
OS engines are never the cheapest, but like all things in life, you get what you pay for and every OS is guaranteed to have the very best quality, time after time.