I gave up on starting the pony after 30 pulls. The spark was weak, but after I took it off and spun it by hand in the garage it was still potent enough to give me a poke, but not enough to make much of a spark when I hooked up the electric drill to it. I read somewhere here that the spark should be able to jump 3/8" if the magneto is in good shape, and with a good strong magnet. Upon disassembly, the innards looked surprisingly good. You have to take note of the position of the timing marks before going too far.

The coil looked undamaged, the wrapping was as good as new, but is there a way to test it with a meter? Any specs?

The magnet is cleverly cast into an aluminum mass that is attached to the main shaft. It appears that there are stacked steel plates visible at opposite ends of the circular aluminum housing that conduct the magnetic field to other steel plates that are cast into the magneto housing and run vertically to the ends of the field coil. That part is probably not in need of any service, but if my problem is indeed a weak magnet in the rotating assembly, how can the field strength be increased? Is this a part that needs to be replaced if the magnetism gets weak? Can these be re-gaussed?

Aside from the magnet, and the spark coil, there ain't much else inside the Bosch magneto that any of us could not troubleshoot by eye. Is there an expert on these, or a good parts source to contact?

Check your condensor, it could be going out.

D2D, yes, they can be recharged, just have to find someone who has the charger..first, how dirty/tracked is the rotor ? and look closely at the inside of the cap for tracks/cracks. Also, you can replace the capacitor at napa for about $12.. and check the points for pitting and white spots..

The cap is old, the condensor has 12 minutes on it and the wires are new...I'll check those out. I could replace the rotor, why not. I'll camp out here a few more days, hopefully someone with info on the magnet and coil pops up!

D2D, those are 'WIRE' core wires, right? Carbons will work for a couple days , then quit. ? is, when you spin the gear, do you feel the rotor magnetic pulses, or does it spin pretty freely? Chances are, it just needs recharged, and or cap since its old, but the cap can be tested too. While your at it, the 3 brushes and springs were like $12..

Bosch Info:

The Bosch mag has no points in it. I mistook this for brushes...OOPS!

What's it got??? I wonder if someone converted it to the "Pertronix" pointless version. Works ok for distributors but I don't know about magneto applications:confused:

If i'm not mistaken if there has been a pointless ignition added it would have to be wired into the coil should be able to trace wiring to find modual? But on the couple of onans I have converted I think you throw the condencer away.
What is the condencer hooked to on this one?
Russell

It's not uncommon to convert the Mag into a distributor and you could go the pointless route, usually with an external automotive type coil. If it is pointless there should also be either a 6V or 12V source going to the (hall effect) module.