CDI Ignition makes the spark by discharging a capacitor loaded
with high voltage (200 - 450 volt) into the ignition coil by using a SCR
CDI coils have low impedance (0.5 - 1 ohm) and can reach high RPM. This
type of ignition makes high power and short sparks.
TCI Ignition charges the coil with a current before the
spark is done. Spark is done when the current is cut suddenly.
TCI coils have high impedance (>1 ohm) and can reach lower RPM. Spark
duration may be longer.