Weird spark issue.

[Sti1472]

I purchased a used off road go kart the other day. The engine is a 150cc GY6. I recently purchased a new rectifier, cdi, and electric choke for it. I installed those items and all is good. I started the engine this morning and noticed something weird. The engine starts and runs, how ever i noticed that while it is running, the rear chain has sparks jumping between the links. Only place i notice sparks. I checked ask the connections i could find and they all look fine. Made site the spark plug boot was on tight. I am kind of stumped. Any ideas would be great