if a cdi is going bad, do they completely quit, or can the thing cause a atv to cut out at higher rpm's (about 2500 rpm)

 

OK, I have to show my ignorance, but what the heck is the CDI? Is it the computer for the EFI models or what?

 

A CDI module has "capacitor" storage of its own and sends a short high voltage (about 250+ volts) pulse through the coil. The coil now acts more like a transformer (instead of a storage inductor) and multiplies this voltage even higher. Modern CDI coils step up the voltage about 100:1. So, a typical 250v CDI module output is stepped up to over 25,000v output from the coil. The CDI output voltage of course can be higher. So you'll see CDI systems claiming coil output capability over 40,000-60,000 volts