Thought I had the problem solved but I continue to have rear plug fouling. If I change out the plug with a clean one and take off no problems runs great no backfire, popping or anything else. However I will occasionally start it up and suddenly it will begin to miss and I know immediatly what the problem is. Pull the rear plug wire and nothing changes - IE running on the front. When I pull the plug it is coated with a sootey, soft black coating. Clean the plug, re-install and runs like new. I believe I have seen this problem posted before but I couldn't find the posts. Is this a leaking valve or worn valve guide? Could I possibly have an intermittent, sticking valve? Please advise!! Thanks!

 

I have the same exact problem with my `77 FL but instead mine is the front cylinder and i still cant figure out what it may be?im thinkin it may be the points ignition i may go with electric ignition.

Thanks