In factory Honda school at Honda's Portland Oregon training center, our instructor Norm Henkel set up a then-new GL1100 with a degree wheel on the end of one of the cams, and after gaining access to the ignition pulsers at the back of the engine, led us students into an interesting discovery.
Not many folks are aware that the first-year GL1100's ignition system had an issue with over-advancing. At first, Honda dealers dealt with the pinging and poor performance by defeating the 1100's vacuum-operated supplementary advance. The trick was to put a tiny steel ball inside the vacuum hose. It became a common thing to do in dealerships. But this didn't really solve anything. As the class discovered that rainy September day, the mechanical advancer was *itself* over-advancing. In Honda school we found that by removing the advancer and carefully squeezing its stop ears together we could return the bike's advance curve back to specification.
But here is the funny part. I and other old-timers in that Honda factory class had seen this problem before on another Honda model. Almost twenty years before, Honda's 450 DOHC did the same thing. Its advancer also over-advanced, and the same solution of squeezing the stop ears was used to correct it.
Strange. You'd think this wouldn't happen; that these issues and their remedies would accumulate in Honda's corporate knowledge base. Apparently not. History does indeed repeat itself.