What has happens (with TWO sets of point so far
) is that the contact point in the pivot arm starts loosening in its mount until the gap stays completely closed.Functionally -- or dysfunctionally more aptly -- as this failure worsens the timing becomes more and more retarded, and as the point gap is also narrowing the spark gets weaker --until the bike stops firing at all.
You can see in the photo that the upper contact is loose to the extent that it has about .020" of extra float in the arm, which is more than enough to close the preset .012" gap. Any breaker action from the points in this condition would be from random vibrations from rattling around in the pivot mount.
The most recent failure occurred last weekend on a 100-mile trail ride, fortunately the bike kept running enough to get back to civilization. For some reason the bike ran better with the headlight turned off. Actually, at idle turning on the headlight shut off the engine like it was a kill switch. In hindsight I suppose I could have worked in some tree pitch onto the contact mount to temporarily stabilize the situation.
As you can see in the next photo I've since soldered the contact solidly in place and now the bike runs great again. Headlight's shining bright at all revs too.
Does anybody have an explanation for this mystery? Incidentally, I also own a 250SL that has a bad and incorrigible habit of shearing counter shafts. That is also on me and me alone so it seems.
