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Some awfully wacky with my push mower, Internal wise.
It's a 3 year old 799983 shortblock (122T02-1207-B1) i bought off of a member on here in Feb. 2019., i go out, check the oil (which i changed in the Fall of last year) right on Full. Topped of the gas, 2nd pull she fired right up, running excellent. I mowed for about 10 minutes, and shut it down, to go move some of the niece and nephew's toys.
Come back to the mower, grab the rope, and it pulls out about 4" and comes to a dead stop, NO way i'm pulling that sucker. I took out the spark plug, put on a glove, and grabbed the blade, i could turn it about 1/3 of a turn either way before it stopped, piston is moving and from what i could see the valves were operating properly, finally after a few times of turning it back and forth, i finally got it to go several rotations with ease. reinstalled spark plug, fired it up, and this thing is vibrating bad. it's not big vibration, just one of those that makes your hands and arms into jello. so i shut it down and finished with the Stihl weedeater. Now i'm typing this. I guess i'll zip the head off and check the cylinder for scoring or anything obvious.
P.S. Blade is still straight, and crankshaft doesn't appear bent in the slightest.

Pulled the cyl head, some very minor scoring in one spot, could not hang a finger nail on it.

Doesn't sound good. Better pull it apart?

guess i'll have to.
And pull out the Old Ryobi push mower with a 123K02 engine, that's had a rod rattle for 10 years and runs perfect with pleny of power

starting to sound like Mr. Connecting rod wants out... pitiful, 2 year old short block.

Welp found the problem, cracked it open. Governor was in pieces.
No other damage. Moderate scoring on cylinder. Kind of funny as the engine speed stayed normal.
Going to remove the rod and inspect the journal.

EDIT
Rod and crank journal surfaces look good, PTO and MAG side journals also look good.

Got the new governor in, sump gasket, PTO and MAG side seals in. But one of the sump screw holes stripped (not the screw, the block) screws are 1/4-20 while i was torquing to 90 inch pounds.
I would like to try my hand at heli coiling it, since i have NEVER used heli coil, at least because i haven't had to. The screw is in good shape but i probably will replace it anyway, but it pulled out the little coil of aluminum with it.
I'm guessing this is the correct set https://www.amazon.com/Helicoil-5521-4-Coarse-Thread-Repair/dp/B0002SRE8Q
or if anyone has a better way, I'm all ears.

Scrubcadet10 said:

I would like to try my hand at heli coiling it, since i have NEVER used heli coil, at least because i haven't had to. The screw is in good shape but i probably will replace it anyway, but it pulled out the little coil of aluminum with it. I'm guessing this is the correct set https://www.amazon.com/Helicoil-5521-4-Coarse-Thread-Repair/dp/B0002SRE8Q
or if anyone has a better way, I'm all ears.

Click to expand...

That kit will do the job. It's a basic, no frills kit, so a little extra care is needed. The coil length will allow maximum strength, but I would suggest backing off the torque to 80 in-lbs.

• Do not drill the hole. The tap does all the work.

• During tapping, remember to go in ONLY 1 to 1-1/2 turns, then back out 1/2 turn to break the chip. Be sure and lube the special tap generously at several depths. WD-40 will do just great. You should end up with beautiful, smooth threads.

• Sometimes I chase the threads from the back of the part because the tap will have a 1/4-20 lead-in which allows you to follow the old threads. Following the old thread keeps the tap at 90° to the work. After tapping, use compressed air to remove all chips. Apply more lube.

• The coil itself is held in by simple expansion. So the coil is LARGER than the hole it's going into. That means the coil will have some small difficulty getting started, going in. Go slow. Once it starts you're good, just go slow. Run the coil in until it's BELOW flush by 1/2 to 3/4 thread. The coils are incredibly hard. If a piece of the end sticks out you may not be able to file it down. You want the starting thread below flush, but you also want the FULL length of the coil captured in the part.

• When you are sure the first coil is below flush (and you can remove the installer tool to check), then you can reach in with small needle-nose pliers and break off the insertion tang. They simply break right off.

► If you screw up, you can pull the coil out like a spring. Once pulled, that coil is dead. Try again with a second coil. Go slow. Use lots of lube. Use lots of compressed air.

Hope this helps.

Bolt hole fixed, governor fixed and she's purring like a kitten now.
Have no idea what was causing the vibration but it's gone now.