Hey bujas,
I have the KDX200 service manual, which is the base manual for the 250. There is also a supplement manual required for the 250, but I do not have it. I could e-mail you the PDF if you'd like. PM me with your address.
I'm in the exact same boat as you otherwise, I just bought a '93 KDX 250 and it's my first dirtbike. I've owned many street bikes but never anything for off road. I too am looking for the KDX 250 supplement service manual if anyone has on they would like to sell or an electronic copy they could post/email.
Thanks