I was just looking at that. The good engine that I have is a 90 model. The 99 model engine that came with the bike isn't worth a dime. Ever case has a crack or whole in it, and there are alot of missing pieces. Even the cylinder has been busted. The good news is that I have my buddies bike borroed right now, and its a 90 model, and needs new kick start gears, so I might be able to get some money for the bottom end I do have. Then I will start saving, or selling, or both to come up with the correct motor.
I don't mind the guy not knowing what he was talking about, when I got the bike from him. That happens. The part that hurts the most is that my bike is a 99. I didn't want a 99. I wanted a 98, which from what I have read is considered the best year kx250 ever made.
But who knows, maybe Iw ill end up with a KX500 motor or something. Time to start doing some reading and seeing wich one is cheaper!