Which type of ignition system uses a capacitor?

The option that involves the use of a capacitor is the capacitor discharge ignition system, which is commonly referred to as CDI. This system operates by storing electrical energy in a capacitor and then discharging it at the appropriate moment to provide a high-voltage spark to the spark plug. This results in a more effective ignition of the air-fuel mixture in the combustion chamber, leading to improved engine performance and efficiency. CDI systems are prevalent in many modern motorcycle engines due to their reliability and ability to produce strong sparks across a wide range of engine speeds.

The alternatives do not utilize a capacitor in the same manner. TDI refers to turbocharged direct injection systems, which focus on fuel delivery rather than ignition. EFI stands for electronic fuel injection, which is also centered around fuel management. Mechanical ignition systems use a different approach whereby ignition timing is controlled mechanically, typically relying on a contact breaker and coil rather than a capacitor.