Topic: 1931 Foldlight with 2 Keyways in the Flywheel.

This topic has 10 replies, 6 voices, and was last updated 1 month, 2 weeks ago by Tubs.

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March 29, 2026 at 10:37 pm #312882
Tubs
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Today I tried starting it using both keyways to see witch one it would run on, # 1 or # 2. Turns out it runs on both. Video – https://youtu.be/lWj45eJLm7A

A "Boathouse Repair" is one thats done without having tools or the skills to do it properly.
March 30, 2026 at 8:39 am #312953
Waunnaboat
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US Junior Member
I vaguely feel like my fold-light also had the 2 keyways…but I can’t remember well. Maybe if I am digging into it I’ll see if yours is not just an oddball motor.

"Outboards seem to multiply exponentially..........I find that for every finished project, there are two more waiting to be completed."
March 30, 2026 at 8:40 am #312954
Buccaneer
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US Member
Interesting, but have to wonder what the original
design intent was?

Prepare to be boarded!
March 30, 2026 at 8:46 am #312956
Waunnaboat
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US Junior Member
I would not know the answer to that question…but I can tell you that I vaguely remember there being a sort of residual imprint of the extra flywheel keyway where grit had collected over the years, so now that I think about it, I am fairly sure that there were two flywheel keyways on my motor (one keyway on the crankshaft end).

"Outboards seem to multiply exponentially..........I find that for every finished project, there are two more waiting to be completed."
March 30, 2026 at 8:48 am #312957
Waunnaboat
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US Junior Member
maybe the intent was to allow one of the keyways to allow for very slightly faster speeds? The flywheel magnets are opposite of each other, so I would suspect that the keyways not being too far off would not pose any major issues on it running, but maybe one is designed so that the magnets line up slightly different. or possibly, they manufactured one keyway and then realized it was a bit off so they then made another across the other side that would work better.

"Outboards seem to multiply exponentially..........I find that for every finished project, there are two more waiting to be completed."
March 30, 2026 at 9:46 am #312961
Tubs
Participant
There is quite a bit of difference as to where the magnets pass over the coils. I positioned the pistons at TDC, just so I know where they are at, and moved the magneto plate to where the points are just opening, when the spark will be produced. Using keyway position 2, the leading edge of the magnet is just a few degrees before the center of the coil. Using keyway position 1, the leading edge of the magnet is about 25 degrees before the center of the coil. There is only one key in the crankshaft. There is nothing in the manual about this.

A "Boathouse Repair" is one thats done without having tools or the skills to do it properly.
March 30, 2026 at 8:25 pm #313087
Waunnaboat
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US Junior Member
I would think that the magnetic field would cause the coils to be charging the condensers no matter what position they are in though? A magnet that is just about to pass the coil when points connect has just completed charging the condensers and would be starting a new cycle? likewise, when it is closer to passing the coil it would be similar?

"Outboards seem to multiply exponentially..........I find that for every finished project, there are two more waiting to be completed."

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Tubs
March 31, 2026 at 10:10 am #313200
GARY
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US Member
I know this request is off topic but I’m still trying to substitute coils in my folder.Tubs photo of his original mag plate would be a big help if he could identify where each of the coil wires (other than plug wires) and the condenser wire are attached to points and to ground.
March 31, 2026 at 10:51 am #313204
jean-michel
Participant
<pre id=”tw-target-text” class=”tw-data-text tw-text-large tw-ta” dir=”ltr” tabindex=”-1″ role=”text” data-placeholder=”Traduction” data-ved=”2ahUKEwjuxsHqrcqTAxWrQ6QEHa3DG3cQ3ewLegQIDBAW” aria-label=”Texte traduit : Hello Tubs,
I live in France and I also own a Fold Light with the same Flywell mechanism as yours.
It also works on both keys. I thought someone had modified it, but I was mistaken when I looked at yours.”>Hello Tubs,
I live in France and I also own a Fold Light with the same Flywell mechanism as yours.
It also works on both keys. I thought someone had modified it, but I was mistaken when I looked at yours.
March 31, 2026 at 12:04 pm #313221
David Bartlett
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US Member
Interesting stuff! I wonder what the original explanation/idea behind this is?

David Bartlett
Pine Tree Boating Club Chapter

"I don't fully understand everything I know!"
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