No active link or photo came through - would love to see it if you have it.
You can find bikes priced by crack smokers everywhere though -
http://kitchener.kijiji.ca/c-cars-v...s-choppers-81-Yamaha-xs400-W0QQAdIdZ550914896
I looked at an '85 xj700 last summer. It was beautiful, like new but he wanted $2k. It was different from the xj650s which were ended in '84 - more upswept exhausts, chrome instrument cases, a different tank etc., but I believe, with 2 valves per cylinder, it's engine was based on the 650.
In '85 or '86 Yamaha also brought out a 700/750MaximX - a 20 valve rocket (5 valves per cylinder). This engine was apparently quite different and the chassis and frame were all redesigned as well.
Do you know if the one you are looking at is the "X"?