Wisconsin S-7D Motor refusing to start

HD, so you think this motor once had a mag rather than a coil? At some point the coil was added?

I found this motor locally and was wondering if it would work for my tractor. Or just for parts. Seller doesn't know what model it is but it comes with a Magneto. They wrote me this

Old wisconsin single cylinder engine with gear reduction.Engine has been sitting,still turns over.

Click to expand...

Thoughts? It's for $25 and an hour drive.

I'd try replacing the original condensor with one designed for the coil,which appears to me to be an old GM car coil that had point style ignition...it might be the original condensor that was used in the magneto died after long use (or sitting) with 12V going in it !..you do not need to ount the condensor where the old one went,just run the wire on it to the negative terminal on the coil (after disconnecting the old condensor!) and ground the clamp that goes around the condensor to a good ground in a convenient spot away from heat...I bet with a good coil &new condensor she'll fire up!..

I had the same tractor years ago with a S-7-D Wisconsin 7.25 HP engine...someone converted yours to use a car coil,it had a magneto originally...nothing wrong with using a car coil,I think its more reliable in the end..sounds like you need to add an ignition switch to kill power to the coil though,you dont want it staying on constantly,it'll smoke the points & the coil eventually...

Oh yeah,that coil is designed to have a resistor in the wire from the battery that goes to the positive coil terminal...GM used special resistance wire,but a ballast resistor off a 70's Mopar car will work fine--without one,the points can burn up fast and the coil might get hot and fail eventually...

In case it has been missed, somewhere. The battery supplied 12v to the coil, through the switch, gauge, whatever, resistor. The 12v goes through the coil, through closed points to ground. It builds up a magnetic field. When the points open, the magnetic field collapses. When it collapses, it forces electricity to flow through the spark plug wire, to the center of the plug, jumps the gap and flows to the head, ground.
The resistor makes the amperage lower, and thus not so much flows through the points, and thus less wear when you get that little 'titch' noise caused by the spark of the points opening. The condenser also absorbs some of that juice, as it wants to keep going, but can't, so side-tracks into the condenser, only to be let out again when the points close once more.
Sorry for the long-winded exposition, but I hope it clears up what is going on in a 'kettering' [I think] spark system. A magneto just creates the EMF [magnetic field] by rotating a magnet on the flywheel past a fixed field, and then dumps the magnetic field the same way, via points to ground opening. I think.
tom

Here is a diagram

Here's the wiring photos from today:




I tried what you said and following the wiring diagram, how can I connect to the condenser then ground? I still got no spark today What am I doing wrong?

I have a kill switch and the wiring has been checked, 12V checked and dead when the switch is flipped. So I know that's working.
In the breaker box in the last photo above you can see the blk alligator clip. That's going to my neg side of the coil. I've noticed when doing this, I'm getting 12V consistently.

Now if I add a 2nd alligator clip on the same screw as the black on and ground it, I drop down to 1 or 2 volts.

The condenser is getting 12vs, the coil wire that goes from the coil to my spark plug is getting 12V consistently.

I press the start button with the switch being on and voltage drops and still no spark.

I followed that wiring diagram above, and breaker points are correct and grounded inside itself from the screw. That diagram says I should ground the condenser, to where? I've tried the neg on the coil and that doesn't work.

As you can tell, I'm at a loss with this thing.

Not giving up, but frustrated to say the least. What are your thoughts?

I got totally confused reading this, so I'll offer this advice: Take a voltmeter, clip the (-) to the negative side of the battery itself. With your ignition switch on, you should have B+ (battery voltage) on the + side of the coil all the time. With the points open, you should have B+ on the - side of the coil. With the points closed, you should have close to 0 volts on the - side of the coil. The diagram TOM603 posted is correct.
If you don't get these voltage readings, post what you get and where. This is not rocket science, but does need a logical approach, and we'll help as we can.

The condenser should be grounded to machine ground.

Reading your post #38, it appears that the points are not grounding the coil primary circuit. When the points close, they ground the coil primary circuit. When they open, they break the circuit, inducing the high voltage out of the coil secondary.

The 12v on the coil secondary is also confusing. The coil body needs to be grounded to the engine, as do the condenser and one side of the points.

Please post the voltages at the various places I mentioned, and we'll go from there.