Is your black box an AC or a DC-CDI?
Here are a few tips:
- If the bike has no battery then it’s an AC-CDI
- What is the size of the CDI? ACCDI are smaller than DCCDI.
Length=6cm then it’s an ACCDI, around 9cm it’s a DC-CDI.
This method is not 100% reliable, some brands use big boxes for ACCDI…
- Age of your bike? Old bikes are mostly AC whereas news one are more DC…
- Search in your Service Manual Technical Specifications for AC-CDI or DC-CDI mention.
- Look at the Wiring Diagram if the CDI is connected to the +12v line or only to the stator:
- What is the reference or serial number printed on the CDI? Google it
- Google your bike with ACCDI and DCCDI key words
- The only reliable way is to measure the voltage between GROUND and the POWER source input of the CDI while the engine is running.
- While the engine is running, disconnect the battery and the regulator,
The engine stall because it has no more +12v then it’s a DC-CDI
The engine still run because it’s powered by the spinning rotor then it’s an AC-CDI
- If the cdi is dead and the engine not running, remove the sparkplug, rotate the engine with a drill attached to the nut on the clutch or rotor side and make the measurements above.
|Ie: On a GY6 CDI measure between GND pin 4 and Power pin 6
If 12 to 15volts DC then it’s a DC-CDI
If 50 to 100volts AC then it’s an AC-CDI
If the bike has a 12v battery, a DC-CDI can replace an AC-CDI but on the contrary an AC-CDI cannot replace a DC-CDI !