You can also use the atc 185 engine from any year. You have to use the 200x motor mounts, and the 200x intake manifold connecting the carb to the motor (different angle). i have done this auto x converesion many times, and it works great if you ask me. plenty of fun for a beginer, or if your too lazy to use the clutch. the other thing is the rear brake lever, I have eheard you can bend the 185/200s lever to make it fit, but I never tried.(because the 200x brake lever mounts the the 200x case)
Hope this helps. GOOD LUCK. ------------ Jon.
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