Do you have the spark pickup air gap set correctly, or in the correct position? (straight up) Have you looked at the wires, and tried a new plug? Unhook the kill switch? Check the manual, and see what it says to do or where to start in the troubleshooting secton for the no spark diagnostic tests. It will give you a few more ideas. Good luck!
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