180° Opposed Twin Cylinder 19.5HP 42E707 2275 E1 Will Only Crank 1/2 Revolution

Another update...

I pulled the heads and removed the valve covers to check the clearances... both intake valves were .002-.003". Both exhaust valves were .005-.006". Bingo, that must be the problem! I haven't yet acquired a valve spring compressor, but after some consideration, I removed the intake valves... carefully ground the stems to achieve .007-.008" without the springs. Re-installed the springs, while saying a few expletives... but got is done. I elected to not remove the exhaust valves as I had so much trouble re-installing the intake valves and they weren't too far out of spec and I understand the intake valves are used for compression release.

Put everything back together.... got my jumper cables... crossed my fingers.... SAME THING. Will not turn over with both plugs installed.

Am I missing something? Or do I simply have two bad starter motors?

I am new to small engines, but I am not new to mechanics... This is getting frustrating! But I am determined to fix this now more than ever.

First thing I would do is use a good set of jumper cables and jump directly from the battery to the starter and see what happens. IF the starter turns over now, you will know the problem is in the wiring between the battery and starter, cables, switches, etc. IF the starter ran OK, use one jumper cable at a time to isolate which side, positive or ground is the problem. You are about out of options. It is not impossible that you do indeed have two bad starters. Have you tried either or both on another engine? Starters for this engine tend to wear the top end/mounting plate bearing oblong letting the armature rub on the fields. Also, holding the starter engaged too long at a time will cause the windings to over heat and loose their effeciency - weak starter.

Walt Conner

Good jumper cables? What are those? I have a decent set, not the best. I have already bypassed all of the wiring, etc... jumping directly from my car battery to the starter.

No I have not checked either starter on another engine, I don't know anyone with a similar engine.

One thing I was just thinking... I am not entirely certain that I checked the clearances nor set them at 1/4" past the compression stroke... I was so focused on measuring the 1/4" that I cannot say for certain that it was the compression stroke.

The top valve is the exhaust and the bottom one is the inlet .
So you poke you pencil down the pug hole and rotate the engine.
You watch the inlet it will open near the top of the stroke and close near the bottom then it will open a gain, just a tiny amount just before tdc .
This is the compression stroke.
The small reopening is the automatic decompression which is why you run just past tdc to make sure you have bypassed the pimple on the cam.
Inlets suck = piston going down
Exhaust blow = piston going up

" jumping directly from my car battery to the starter."

You are missing the point of this test, jumping from car battery doesn't do it.

Walt Conner

bertsmobile1 said:

The top valve is the exhaust and the bottom one is the inlet.

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No, you have it backwards.

Tinkerer200 said:

" jumping directly from my car battery to the starter."

You are missing the point of this test, jumping from car battery doesn't do it.

Walt Conner

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What am I missing? I am eliminating all of the circuitry on the tractor, to simplify the troubleshooting.