The thing under the circle cover is called a Pulse generator. is the ignition timed correctly? Check the Pulse generator gap. It could be the stator you check the black wire with red tracer which is the power and ground it to the case. I can make a video showing you how to check the stator and pulse generator tomorrow if you want. Just Pm me if you want me to make a video, its easier than explaining.
1983 ATC 185s 200 jug bored .20 9.5:1 Naumura piston. Fast as ass when its not stretching the drive chain or stripping hubs.
1986 ATC 250ES. *Total garbage trying to sell it*
1983 YTM 200E. Runs good, forks are super bent but aside from that its mint.
1984 YTM 200L. Barn find, everything is mint except the bottom end is bad... *waiting on a new engine*