Sounds like it could possibly be a wiring issue. Take off the tank, and see if there isnt a bad connection or damaged wire making contact with somthing it shouldnt. Also, the kill switch can do wierd things sometimes before it goes out completely. Try unhooking it from the wiring harness, along with lights (same housing) and give it a try. If it didnt help, then you know thats not the problem. 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