Before ordering, check whether AC or DC fired CDI is needed
If you have 3-wires going into the 4-plug side and 2-wires going into the 2-plug side you have AC Fire system.
If you have larger CDI box, 3 or 4 wires going into the 4-plug side and only 1 wire going into the 2-plug side, you have DC fired system.
Usually, DC CDI's tend to be larger in size than the AC ones.
Common AC CDI dimensions (LxWxH mm): 65x36x 22 or 58x33x22.
Common DC CDI dimensions (LxWxH mm): 75x42x24 or 96x55x24
Please note, reference dimensions not meant for racing CDIs
If engine will only run with battery, it is DC fired system.
If engine will run without a battery, it is a AC fired system.