Here's a thread i made a while back. It's literally the exact same problem. It's a different stator, and bike all together but the operation conditions are the same. but that treats CDI is notoriously bad.
Check the exciter coil for shorts the wires on them are pretty thin and tend to get fucked. You will probably need to rewrap or just replace it.
actually, you replied to that thread at some point. (edited)