I just completed rebuilding the magneto for my 1964 CH. I had the rotor re-magnetized, replaced all seals, bearings, cap, condensor, etc. The only original consumable parts that remains are the point assembly and the field coil, as they are original Faribanks Morse and they are in very good condition. My experience with the field coil is that if they check out with a continuity tester and if the secondary winding does have continuity to ground, then the unit is probably good, as they rarely go bad. Plese correct me if I'm wrong here.
I then bench-tested the unit to make sure that it sparks, and it does. I attached new spark plug wires and spark plugs and spun it by hand and it fired the plugs. All is right with the world.....
HOWEVER, I have become somewhat obsessed about magnetos. I severely damaged my knee after buying my first Sportster in the in the 1960's. We all know the scenario; worn kicker gears and bushings, low magneto spark, a strong right leg, little expereiece, and more balls than brains. 'If it doesn't start, kick it harder and faster'.... This injury as remained with me and at this age, I don't want to re-injure myself. Therefore, I have (incorrectly) installed the 1965 and later advance/retard plates.
My concern is this; in my memory of ancient times I seem to recall that when hand-testing the magnetos that I rebuilt, they were able to produce a very strong blue spark that was clearly visable in daylight. This unit produces a consistant spark, but it is light in color under flourescent lights. Turn the lights down and the spark appears blue. Also, when I open the spark plug gap from 0.015" to 0.025", the mag has no problem bridging that wider gap. With the cap removed and a grounded screw driver placed close to the field coil springs, the unit produced a spark, but again, it appears lighter (blue/white) than I recall. Also, with the screw driver place BETWEEN the springs the unit won't fire from both springs to the screw driver - the gap is apparently too wide. I seem to remember doing this double-spark check years ago, but I'm not sure. Also, this rebuilt unit is a little stiff to spin fast by hand with the re-magnetized rotor and the new seals. Finally, Just to rule out the field coil, I tried two other used coils that I have (one with the Faribanks impressons and one that appears to be aftermarket) and both yielded the same spark intensity.
Its my opinion that low-intensity output is probably the main reason why these magnetos are dis-favored by some and probably accounts for much of reason why some Sportsters start hard and why there were so many worn kicker gear bushing and rounded clutch hub tooth problems so common in older Sportsters. I just want to make sure that this problem is fully addressed now and that I have confidence in the magneto before I install it. But I would just hate to send it out to a magneto shop for needless testing if I'm just being over-concerned.
My guess is that my memory is wrong and that this unit is fine. However, I would appreciate input from guys that have remained more current with these magnetos than I.
Huntington, New York