I wonder if he routinely used ether starting fluid.
Ether is so explosive that it can actually flex the piston slightly.
Without any other evidence of galling damage on the cylinder walls I would personally suspect an "ether guy".

Good point mownie. You're probably right on. I heard the jingle of money in the crankcase when it whirred over. It had good enough compression, valves looked good on top, key good etc. I guess I was a bit surprised. I had the thought that maybe they started to pop composite cams in these and had jumped a tooth. Lube was good enough to keep the journal and rod end happy. He wants to shorty it at 7/8 the cost of a new tractor rather than waste it. I guess credit is due. Anyone need a cam, crank and rod for a 219807? :)

Supposing,just supposing. What if you opened the engine, scooped out all the aluminum, wiped it down, and buttoned it up? As for ether, I've been using it with varying degrees of success for over 50 yrs. I have never blown up an engine from using it. Just lucky, I guess.

Well, though the journals are relatively fine- the walls of the cylinder are gouged nicely. It tore the piston side off at the oil ring on the valve side. It leads credence to mownie's hold your ears and hear the boom theory. More metal to donate!If I've seen a piston do that in the past, I figured it was from the baling wire tied to the carb ...

As I stated in my first post ***"Without any other evidence of galling damage on the cylinder walls I would personally suspect an "ether guy."***
If the cylinder walls "are gouged nicely".....as now reported......I would be more inclined to blame the failure of the piston skirt on the galling and gouging rather than ether.
Whether the gouging occurred AFTER the section of skirt broke away (allowing the piston to tilt and bind against the cylinder wall)....or if the skirt broke away after the piston galled and tried to seize to the cylinder wall......could only be determined by examining the broken piece of skirt.
If that piece of skirt appears relatively unblemished, the gouging happened AFTER the skirt broke off.
If the piece of skirt also shows the nice gouging.....it broke off as the piston tried to seize to the cylinder wall.

But "ether way", it's not wise to use ethyl ether based starting fluids in these lightly constructed engines.
Far easier on the engine to just spray a small shot of aerosol can carb cleaner into the carb throat, or even dribble a spoon of gasoline into it for cold starts, if a particular engine seems to need more than an application of choke to get it going.

You were right the first time Mownie. The cylinder walls were damaged by the piston after it came apart on the valve side. Hardly a mark anywhere else. Lightly constructed is the key!