That DB article is good, except for the bit about the motors being based on KX125 motors. There are similarities (conrod, gearbox) but the 200 motors were always significantly different to the KX125 motors.
The various models of KDX200 all used the same architecture: bore; stroke; rod; shaft spacing; mounting points.
It's more accurate to say that the KDX200 motor was a stand-alone design from the start, and was progressively upgraded over the years.