They are basically the exact same as the 85 tri z, except for the color differences in plastics and frame. The 86 Tri z is the rarest of the 3 years, and most sought after because of the 6 speed transmission, and slightly beefier forks, which isnt somthing you cant live without. The 85 trans is def. better on a track, and especially drag racing/take off speed. Mostly all the parts from the 85 - 85 1/2 - and 86 will interchange. The tri z's are pretty unique at the way they handle, and the way it feels when you sit on it, almost like you sit "in" it, which makes for a comfy ride. They are a little more difficult to work on in my opinion, because of the vacuum lines, and fuel pump coming from the rear gas tank, but still well worth it. Good luck, and ask away if you have any questions!
THE 80's RAGE! Currently owns:
81, 85 Yamaha Tri Moto 125
83 Yamaha Tri Moto 200 x2
82,83 Yamaha Tri Moto 175 project
85 Yamaha Tri Z 250
84 Kawasaki Tecate 250
84 Honda ATC 70
85 Honda ATC 350X
84 Honda ATC 250R
(2) 84 Honda ATC 200x
82, 83 Honda ATC 185s
81 ATC 200
Lots of other parts and bikes