AC 5 pin CDI for 4 Stroke 50cc 70cc 90cc 110cc 125cc Horizontal Engine ATV Dirt Bike Go Kart5 pin AC CDI; Dimensions: 4.41 x 2.2 x 2.13 inches. AC 5 pin CDI Replacement for 4 Stroke 50cc 70cc 90cc 110cc 125cc Horizontal Engine ATV Dirt Bike Go Kart. CDI stands for motorcycle ignition in the form of electronic ignition. The working principle is that the high voltage electricity emitted by the generator coil passes through the electronic igniter, then passes through the high voltage package and subsequently through the spark plug to complete the ignition process. Unlimited CDI adopts high quality plastic and metal, with professional manufacturing facilitating installation, ensuring a long service life. Plug and play, ignition energy intensity, powerful acceleration. Dimensions: 4.41 x 2.2 x 2.13 inches.