Absolutely it is possible the coil or the built in CDI is toast. It was a bit of a bad design really. I had to replace the one on my old 650sx too. If you are trying used CDI's you could have two bad ones. I'm sure if you searched the net you could find a service manual for it, they do offer testing procedures for the CDI but I can say from experience that Kawi has been very hit or miss with their values on CDI testing. I tested a brand new CDI from Kawi when working at the dealership for a 750 runabout, both new and old CDI's tested exactly the same when comparing to each other but were nowhere near the values they listed in the manual.