I have a 07 400ex that seems to keep burning up CDI boxes. It had a aftermarket CDI on it when I got it. I have put a new OEM CDI on it with a new stator it started up for about 5 minutes and stopped running. Now it has no spark again and seems like the CDI is bad again. What is causing this? Any help would be great.

 

The most common causes of this are a bad earth on the CDI. Make sure that earth wire has no resistance on it. Alternatively, on some Hondas, battery power is also fed to the CDI. If the regulator is overcharging the battery, this can feed too many volts to the CDI, and blow it.