Speeditwin 6039 22.5hp only firing on one cylinder

[bsplit]

Before I pull the flywheel, am I right in assuming that, since both cylinders use the same coil, condenser, and points, the problem is in the spark plug wire? It’s not a problem with the spark plug. I switched the plugs and both fire on the port side, but neither fires on the starboard side.

Thanks,
Jim

[david-bartlett]

The speeditwin uses one coil for both plugs, BUT, there are two tabs on the coil for the plug wires to attach too, so you could have a bad solder joint or a bad winding inside.

[bsplit]

Thanks…..I did see that one end of the coil was "scuffed up" before I replaced the flywheel. That my be the problem. I’m not sure how I damaged it, as it wasn’t that way when I got it.

[david-bartlett]

Good used coils are out there, There were a lot of these motors made.

[bsplit]

Thanks, Dave

[Tom]

What is the resistance between the two spark plug wires? What is the resistance between each wire and ground?

I’d try to track down a short in the side that doesn’t fire, (or even a blockage of fuel to that cylinder). Since there is only one coil firing two cylinders, the coil is likely good. One way to look for shorts is to ground the good side directly to the motor. Then attach the wire of the bad side to a grounded spark plug and turn the flywheel by hand in a dark area. If there’s a short in the "bad" wire, you might see the spark. It could also be under the flywheel, in which case you’ll need some kind of magneto tester, or fire the coil with an external battery.

Tom

[bsplit]

Things went from bad to worse on the Speeditwin. I checked the coil with my Mercotronic….hope I did it right. I grounded one spark plug wire while checking spark on the other, and then reversed the process. My Mercotronic showed spark on both sides, with a hotter spark on the side that was not firing.

Before checking the coil, I replaced the starboard spark plug wire with a new wire.

Anyway, I’m now not getting spark on either side. I’m going to let that motor rest….maybe tackle it in a couple of days. It’s a real pain removing and torquing the flywheel. Not so bad getting it off, but with the weird flywheel nut, I had to jury rig a setup to torque it down with my torque wrench.

Thanks for the help,
Jim

[bill-loveland]

Try a crows foot socket

[bsplit]

Thanks, Bill….that’s what I used…..but my torque wrench is 1/2 inch, and my crow’s foot is 3/8 ……so I jury rigged it so I could use my 1/2 inch torque wrench.

[bill-loveland]

Technically, you should make an adjustment: http://www.engineersedge.com/manufactur … ench_1.htm

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