I just fixed a spark issue on an 84 200S today, take the cover labeled CDI off the top left of the engine, remove the two phillip head screws that you can see hold the pulse generator plate(round metal plate, magnetic) orr, and make sure the bolt is in the end of the generator shaft, if it's not, or loose, or anything, just try and pull that magnet out with you hands, if it's will slide out ANY, the small pin holding it in could have came out(very, very easy if the shaft moves), that causes the shaft not to align with the magnets correctly, and cause either no spark, or a bit of spark every now and then.
It sounds complicated, but it's a very simple process, you'll need a ratchet with an 8mm socket, a philips head screwdriver, and if the bolt is loose, a 10mm socket.
I tried EVERYTHING with that darn S, and I just thought about that, looked, and bingo was it's name-o.
This is my trike. There are many like it but this one is mine. My trike is my best friend, and it is my life. I must master it as I must master myself. My trike without me is useless. Without my trike, I am useless. I must ride my trike true. My trike and I know that what counts is not the amount of miles we ride, but the time we ride together. My trike is human in it's own ways, therefore I will learn it as my brother. I will learn it's weaknesses, it's strengths, it's parts, and it's soul.