so i just picked up this sj a couple weeks ago. I took it out to the lake and it started great and ran for 15 min till i came in to the beach and shut it down when i went to go start it after being on the beach for 15 min it had trouble starting but did and i went out again ran fine came in shut it down but the third time i had no luck starting it figured out it had no spark. the next day it fired right up check spark and there was lots went to the lake rode it once and then wouldnt start agin check the plugs and no spark.

the ski came with an extra coil so i put it in and had no luck same problem. so this is as far as i have made it i dont want to buy any parts i dont need i have done some reseach and maybe cdi? any help would be great thanks