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What kind of information are you looking for?
The mag in my Johnson HS-10 just about put me over the edge a few years ago trying to get it to work right. I think Buccaneer has had some experience with these mags to.
Here’s a previous post about these mags.
If I remember correctly, this coil with the carbon brush setup was to make the alternate firing
twin run with a single, double secondary output coil, by grounding out the cylinder that’s
not suppose to fire, via one of the carbon brushes, and a ground circuit in the flywheel.There’s a bakelite piece riveted on the inside of the flywheel with a little “contact spring” that’s
suppose to be the coil grounding path.What I ended up with was the most irratic running motor I ever worked on.
It’s a magneto problem for sure, and in retrospect, thinking about it now,
I bet that the one cylinder is partially “sparking” the plug when it’s not suppose to.I have a video of it running, but I’m not finding it on YouTube right now.
If there’s interest, I can try to post it there.
Perhaps this would be a good motor to re-visit, but thanks for reminding me of my defeat, lol
Prepare to be boarded!
Those things gave me a fit back in “The Day” because I really didn’t understand them. But with what I know now, they aren’t all that complicated. It helps to first understand how it works as applied to horizontally opposed twins (picture below). When voltage in the secondary winding is high enough, the electrictal flow is as follows. It flows from one end of the coil, to a spark plug, jumps the gap to ground, THROUGH THE GROUND back to other spark plug, jumps the gap, and returns to the other end of the coil, completing the circuit. Thus, both plugs fire at the same time.
With alternate firing twins, one end of the coil secondary is grounded by the carbon brush, Now the flow is from the ungrounded end of the coil, to the other spark plug, jumps the gap to ground, and back to the end of the coil that is grounded by the brush, completing the circuit. When it is time for the other cylinder to fire, everything is reversed and the other plug fires.
Nice explanation and graphic Frank.
Back when I was trying to figure out the very erratic running HD-15
with this “whacky” ignition, I did some testing and made a diagram
trying to make sense of if things were working correctly as far
as the coil grounding system.Thinking back, all I know is I was using an ohm meter checking continuity
as I slowly spun the flywheel. I have no recollection of if the points,
and condenser were hooked up or not, but I remember getting readings
on the meter that made no sense.
Perhaps one day I’ll try again, but maybe with a different flywheel if I
have one, or can find one.
Prepare to be boarded!
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