The term 'CDI' is often, incorrectly, used to describe electronic
ignition systems. Most modern ignition systems are actually
Inductive Ignition systems for good reason, especially when
using lean burn fuel mixtures. Inductive ignition systems
can provide prolonged spark duration; resulting in more reliable
and a cleaner burn in modern lean burn engines (see diagram
3).
Capacitive discharge systems may have advantage in older 4-stroke
engines, an engine running beyond its service life, or a cheap
2-stroke engine. These engines will be running an oil rich
/ fuel rich mixture, which may cause fouling of the spark plug
gap. The higher initial discharge of a CDI system may be able
to 'burn' off these deposits better than a comparative inductive
ignition system.
