Cub 1864 Ignition coils

[J-Mech]

Failed plug wire?

[Rodster]

I thought about that. I checked the resistance from the legs to the plug wire and on both coils it's around 8k ohms. However, when the tractor wasn't running on two cylinders, I checked that wire with a tester and there clearly wasn't any spark.

After I changed the coil I was hoping it wasn't simply the plugs I installed last year.

Mowed twice with the new coils and all is well so I guess I can rule out the plugs as the culprit.

Could be an intermittent problem that won't show up on the bench.

[jdroison]

there is a solid state trigger built into the coil that opens the circuit at the right time. its just like the add on ones that you can get that just clips on the side of the coil to replace the points on the older engines, but are now built inn.

[J-Mech]

Originally Posted by jdroison

there is a solid state trigger built into the coil that opens the circuit at the right time. its just like the add on ones that you can get that just clips on the side of the coil to replace the points on the older engines, but are now built inn.

No, there is not. The magnet is the trigger. How many times do we have to say it???

[Gaden]

A bad coil won't always test bad on the bench, often times they will only fail when they get hot.

[Gaden]

Originally Posted by jdroison

there is a solid state trigger built into the coil that opens the circuit at the right time. its just like the add on ones that you can get that just clips on the side of the coil to replace the points on the older engines, but are now built inn.

http://antiquepower.com/how-does-tractor-magneto-work/

[J-Mech]

A magneto that is on an old engine is different than these though. The old Mags used a set of points to collapse the field. The mags on these small engines don't need points. They collapse when the magnet moves away from the coil. They are similar things.....yet very different.

[Mike McKown]

Originally Posted by jdroison

there is a solid state trigger built into the coil that opens the circuit at the right time. its just like the add on ones that you can get that just clips on the side of the coil to replace the points on the older engines, but are now built inn.

B&S brought out an ignition in the '80's called Magnetron that worked like you describe. That's when ignition points were eliminated from the ignition.

Maybe this is what you're thinking?

[Gaden]

Originally Posted by J-Mech

A magneto that is on an old engine is different than these though. The old Mags used a set of points to collapse the field. The mags on these small engines don't need points. They collapse when the magnet moves away from the coil. They are similar things.....yet very different.

Right, I was simply providing information that there is no internal trigger mechanism, only spinning magnets. The site described both types.

[FrankF3]

Originally Posted by jdroison

there is a solid state trigger built into the coil that opens the circuit at the right time. its just like the add on ones that you can get that just clips on the side of the coil to replace the points on the older engines, but are now built inn.

jdroison is 100% CORRECT! Back when I was in engineering, we used to get design magazines all the time. In one issue was a write-up on the Kohler Magnum Magneto Ignition system that was recently designed and hailed as an engineering design feat at the time. Below are pages taken from a ACTUAL Kohler Electrical Systems Manual and the pertinent pages that describe the theory of operation of the Kohler Magnum Magneto system. Make note of the KEY feature of the trigger coil built into the magneto.

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