I can tell you from first hand experience stator failure is common on '83 - '85 KDX200's.
When mine failed back in the day, it started out being heat sensitive (bike would die when it got hot, then not restart until it cooled down a little).
Then it got worse - hard if not impossible to start cold, and when it would start, bike would die sooner and take longer to cool down enough to restart.
Finally, it would not start at all, no matter what you did.
Rewinding the stator fixed it.
BTW, my stator would measure within spec (the old '84 manual had resistance specifications), which made this a tough problem to diagnose.
FWIW, I did have my flywheel key shear on that bike too, but it would not run at all when that happened.