I suspect the charge diode may be bad. This may have ruined the stator.

If you look at the schematic on page 29.
There are 2 wires coming from the stator.
One is AC volts going to the head lights.

The other (which is what we care about) starts as AC volts, goes through the diode where it is converted into pulsating DC volts for battery charging.
The diode acts as a "check valve", only allowing the + part of the AC SIN wave through and blocking the - part of the AC SIN wave.

IF- The diode is shorted, you get AC through, which KILLS batteries.
IF- The diode is open, nothing gets through.

You'll need a volt meter to test the stator.
The schematic shows where to test and if you should have AC or DC volts.

To test the diode, use the OHMS scale.
Try ALL the ranges in BOTH directions. (some of the ranges simply don't work because of the voltages/currents used)

IF A diode is good, it will show continuity in ONE direction ONLY!
Continuity in both? BAD, shorted
No Continuity in either? BAD, open

Find the "2 wire harness" that leads to the engine (1 red wire and 1 orange wire).
The red wire is the one that handles charging the battery.
On the engine side of the plastic connector (red wire) you you should be able to find a small lump wrapped in heat shrinkable tubing.
The lump is the rectifying diode.
Unplug the connector.
Using an Ohmmeter, touch one test lead to the red wire terminal in the engine side connector, touch the other lead to a clean unpainted surface on the engine.
If you get no reading of continuity, reverse the test leads and check again.
If you get no showing of continuity in either position of test leads, the diode is open and that is your charging problem.
A good diode should read continuity in only ONE direction.
If the test shows the diode to be good you will need to check the red wire from the chassis side of the connector to the key switch for an open circuit or maybe defective terminals at the key switch.

Hard cranking is typical of this series engine. I have a list of the most common causes IF you would like it, address below, put in proper format and remind me, model number and what you want.

Walt Conner
wconner5 at frontier dot com

Thanks for the responses. I was about to give up, but after reading the advice given, the thrill is back. I will report back after running the test.

Please forgive ignorance; Electrical testing is not my greatest knowledge. Do I test the diode with the engine running?

Ohms is a measure of resistance.
YOU never want to have voltage present when using the OHMS scale.
The battery in the meter supplies the current.

Ok i used the multimeter and set it to check diode. The meter remained at 1 with one check and when i reversed it i received a 3 digit number. If im correct does that mean the diode is good and my problem is somewhere else?

Thanks for all your help.

As I said-
To test the diode, use the OHMS scale.
Try ALL the ranges in BOTH directions. (some of the ranges simply don't work because of the voltages/currents used)

A 3 digit number is meaningless if we don't know what the reading actually is.
What digits? What scale? Where's the decimal point?

Using ohms set on 20m, i get no reading in one direction. when i reversed it the reading is 10.25 (black lead connected and red lead against the engine).

***"no reading in one direction"***
That declares the diode to be good.
Answer a few questions please.
At the present time, can you turn this engine by hand (or with the starter) with the spark plugs removed?
I ask it that way because of the lines "After use it will not start even with a jump and new battery. Now it has a burning smell from the engine."
The "burning smell", the "killing of new batteries", and the "no start even with a jump" seem to be pointing to something other than just a charging problem.
So, knowing that the engine will still rotate a few turns by hand will at least get us beyond the possibility that the engine seized when you shut it off the last time it ran.

As mownie says, DIODE is good.

Just to clarify things a bit-
Does the mower start? (even if you have to jump it etc.)

IF it will-
Check battery Voltage (DC) before starting and after.
Report back what they are.
IF it's charging, you should see a definite increase to above "nominal" battery voltage at HIGH engine speed. (>13 VDC)

You might also check the oil level to make sure the "burning smell" isn't the engine itself.

Also, I forgot to add-
You can actually try the "proper" test of the stator.
Disconnect the plug that has the diode in it and check
- AC Voltage BETWEEN the diode and stator to see if you are getting 28 VAC minimum, at high engine speed.

Thank you, Bill K. That is good to know. Mostly, I get my info the hard way. Last diode I tested was on my car. So knowing where to do it on OPE is a good thing.

Engine does rotate but i realized that I now have a broken flywheel key. Which is why it will not start. I will report back with the results of the battery test once I replace the key.

Failure to torque the flywheel nut or bolt to 150 foot pounds will result in a broken key.
The correct way to install the flywheel and key is to have the taper surfaces of the crank and the flywheel completely clean and free from any dirt or oil.
Set the flywheel onto the crankshaft with the keyways aligned.
Finally, insert the key into the keyways and tap it down gently.
Install flywheel fasteners and torque to 150 ft.lb.

Can I use an impact wrench to get the 150 foot/pounds?

Realistically speaking.......not a really good idea to start guessing with an impact wrench for tightening .......... unless you have a lot of keys, and a spare crankshaft.
There are "economy model" torque wrenches available for the DIY folks that will fill your infrequent needs for a torque wrench.
And also looking at the basic idea of the DIY concept...a portion of the significant amount of money you save by DIY should be applied to some necessary special tools for the critical things......and torque values are critical to ensure against too little, or too much, load applied to fasteners and their subject components.

Agree with Mownie. Here's an example of a low cost torque wrench....

Here is a link that might be useful: wrench

Thanks. That would mean getting a flywheel holder also to keep the flywheel from spinning. Any ideas to where to get an inexpensive one. My nearest cycle and turf wants $85 for that tool.

rather than spending $85, I might get me a 4' length of say 1/4 dia. nylon rope in good shape - touch a match to one end to burn off all the loose ends - turn the engine crankshaft till the piston is retracted - feed some of that rope into the cylinder thru the open spark plug hole making a coil pile - turning the crankshaft until the rope is compressed by the piston - torque my flywheel to 150 lbs - remove rope - save that $85 to treat the wife for dinner out ?

I concur with what rcbe said. On this engine you can actually feed a bit of rope into BOTH cylinders as the pistons are synchronized, one of them will be on compression and the other will be on exhaust, the load of holding the crank will be shared by both pistons this way.
Happy Thanksgiving day

Ok i put everything back together but still not starting not even with a jump. When ithe turn it over it spins but sort of drags. I get no fire. Unless someone can help i guess i'm at the end of my rope. To the shop it goes.

If you HAVE NOT sent Walt an e-mail as he offered, you should do so and get his list of typical causes of slow/no cranking.

I sent Walt an email asking for info. Thanks. Should I start a new thread since my problem seem to be different now?

Since YOU are the person who began this thread, you can continue to use it for issues pertaining to this engine until some kind of resolution is reached.
When/if you get past this and have a running tractor again, you can begin a new thread at another time for a different problem.
My opinion is that the tractor still has some issues that were part of the original posting and it's perfectly OK for you to stay on this thread to completion.
That way a reader can scroll through the entire discussion without having to swap threads.

How cool is the weather where you are? If the tractor is outside, and it's pretty cool, that may be some of the trouble.
I have one of these engines (422707) and if I really need to use it in temperatures below about 40 degrees F. I must warm the engine with a heat lamp or I can put a 1,500 watt portable heater in place to do the same.

Mownie makes a good point. IF you are using a straight 30 weight oil and it's cold, that will slow the cranking.