You want facts? Go do some work on small engines. Rusty armatures, and rusty magnets will affect spark strength. Magnets do not have full strength when they have to power through rust, not having full strength WILL cause weaker spark!! Cleaning the magnets, dosnt nessicarily have to be sanding, it can be a wire brush will remove the rust thus removing the "barrier" between armature arms and flywheel magnet. Have you ever worked on points ignition systems? If the points are dirty or have any corrosion on them, its basically the same principle, you get weak or no spark. I had this problem last week on a 28ci. Barely any spark, cleaned magnet and armature and bingo bright blue spark. You say electricity dosnt pass through them, but a magnetic field does, which can be broken or disturbed, as I stated above.
Well if you have test data and results i would be happy to see it!
And sorry, but unless you own your own small engine repair business and it is very large, I have much more experience than you do. Yes I have worked on points.
I have worked on some of the very first Briggs and Stratton engines, that had the entire ignition systems contained inside the flywheels (no points plunger) that were chain driven kick start, as well as everything in between up to brand new Briggs & Strattons. Heck, I've worked on engines that didnt even have electrical ignition.
First thing, is that with points, electricity actually passes through the points and the condenser. Electicity does not travel between flywheel and armature. Therefore, the given illustration is void. The typical amounts of rust between the flywheel and armature would not change the voltage produced. End of story.
Another thing is you say "bright blue
spark" The color of the spark has nothing to do with the strength, voltage, or duration of the spark. This is another FACT strait from Briggs & Stratton research (as well as anyplace else that researched sparks) . The color is affected by many things such as the gap, the type of metal it is jumping between, and what is in the air the spark is traveling through to get to the other electrode.
Sorry about this to all you folks who arent in this.
But, it just really bugs me when somebody ensists something is true, but has nothing to back it up with.
Happy building and racing!!