Continuation of my last post....
THIS ONLY APPLIES TO TWIN TOWER BMW COILS
Decades ago, when BMW went to the single coil setup on airheads, a lot of customers complained that their bikes were starting on one cylinder when cold, and running intermittently on either cylinder until warmed up a bit. Sometimes this lasted 5 seconds, sometimes a few minutes. Both exhaust pipes would get hot
immediately, proving that both cylinders were firing, but it sounded like the bike was running on one cylinder. After a certain delay it would suddenly get smooth, as if an invisible switch had been activated, and then it would run perfectly and not do it again until the next cold start. Colder temperatures exacerbated the situation.
I was working for a BMW dealership back then. We spent hours trying to figure it out, and we finally did.
BMW was of no assistance. They said it was normal, just a slight inconvenience, and not a safety issue.
It turns out, most (if not all) of their coils produced a weak orange spark for a few seconds (or minutes), making the bikes run like crap, and then suddenly, for no apparent reason, the spark turned to bright blue and all was perfect.
I've installed many dozens of these Accell coils on airheads and Harleys, they always resolved the above issues.
I just replaced my 1990 Accell coil a few years ago. It half died.
Accell used to have a lifetime warranty on their products, but no longer does.
My Accell rep could not believe I wanted a free replacement for a defective part that was older than him.
I still had their "lifetime warranty" printed on my original instructions from 1990 in my folder.
After a half dozen discussions with staff on escalating echelons of the Accell hierarchy, they finally gave me a new one at no charge just to get rid of me.