Lotsa head gasket failures for sure. Smokes like grandma at the black jack table....

I did a leakdown test on it. It doesn't hold pressure well on the right cylinder. The plug was dry, but oil fouled and while under 50# of air pressure, the other gauge was about 25# and pressure was escaping out of the breather hole if I held my finger over the hole to let it build up, which is above the right side valve cover.

I can hear the air escaping, but now that you bring up a head gasket issue, I'm not sure if it leaking past the rings or past the head and into the valve gallery.

How do you suggest I would separate the two issues without pulling the head?

It smokes upon start-up for about 45 seconds and then burns pretty clean. It uses about half a quart of oil in an hour or so.

Pull the valve covers, look down the pushrod gallery with a strong light while you pressurize the cylinder. If the head gasket is leaking as bad as you have described the escaping air to be, you will be able to see it escaping into the pushrod gallery.
Evaluating piston ring condition can be done by a dry compression test followed by a wet test.
Dry test: connect the compression gauge, block the throttle wide open, crank engine so you get a minimum of 4 compression strokes registered on the gauge. Record the reading.
Wet test: Add a couple teaspoons or a few squirts of clean motor oil to the cylinder through the spark plug hole. Connect compression gauge and crank the engine until a minimum of 4 compression strokes register on the gauge. Record the reading.
Compare the 2 readings. An increase of pressure amounting to 10 or more PSI for the wet test indicates the rings have worn.
To confirm ring wear during a teardown of the engine, the piston rings should be carefully removed from the pistons so you do not break the rings.
Then place the rings into the cylinder they were running in and measure the ring end gap. Compare your measurement to the engine specs in service manual.

OK, I'll try that. Thanks.

I've always wondered how oil would distribute to the entire piston head in a horizontal cylinder for this test.

The owner said the smoking started suddenly when he was mowing an incline and has been that way for almost a year.

Yes, you can hear the air escaping. It's not subtle at all.

Baymee, I may have given the wrong impression to you about the "dry/wet test" in this specific case.
I did not realize how my post might be misconstrued until I read it again today.
The dry/wet test IS NOT suggested as part of the evaluation of piston rings if the engine has another compromising defect (such as "blown head gasket") that has already been confirmed.
The dry/wet test is actually intended to help one determine whether LOW COMPRESSION on a cylinder is due to a defect in the valves/seats............or whether it is due to worn piston rings.
A significant increase of compression after adding oil to the cylinder indicates worn rings.
No increase of compression (wet test) usually indicates that the condition causing the low compression reading on a cylinder will be found in the valves area.
As to how oil will distribute evenly (when the pistons lie horizontal): Piston rings are not rigid components pushing against the cylinder walls and piston ring grooves to affect a tight seal all by themselves.
Piston rings are actually "inflatable devices" that expand against the cylinder walls, and the lower portion of the ring grooves (ring lands) when the pressure of compression acts upon them.
Because of this "inflation process", some gases will escape past the rings to the crankcase before the rings fully inflate (blow by). The condition worsens with advanced ring wear.
But because any oil that is introduced to the cylinder for a "wet test" will also try to follow the escaping gases as they blow by the piston rings, enough oil will be "force fed" to all the surfaces that play a part in inflation of the piston rings.
In this particular case and on this subject engine, if you find a blown head gasket on one head.........a dry/wet test would not help determine if the piston rings are good on THAT cylinder.
But, if the opposite cylinder does not have a blown head gasket, a dry/wet test could be done there to give an indication of ring condition.
And let me add that only when a cylinder actually shows to have less than specified compression pressure, would a dry/wet test need to be done. An engine with normal compression across all cylinders does not need to be evaluated this way.

Personally, I would just pull it apart. These don't necessarily blow in the push rod gallery.

You mean I should pull the head and check the gasket?

You might just remove the valve cover and start the engine BRIEFLY.
You'll probably see obvious "vapor" blowing out if the head gasket is bad.

Last one I had blew between the cylinder and the oil return. I've seen that before. It pressurizes the engine either way. The service manual would be a good thing for you. there are a few things that can contribute to your problem. There is a small reed on each side in the block behind to verify is still intact also when the head is off also.

I took the head off today. I wish there was a leak between the cylinder and the valve area, but there isn't proof positive. The exhaust valve has alot of carbon buildup and the head gasket looks like it might have been leaking on the lower side. The cylinder looks good with the cross hatching still apparent and no marring inside.

The other side of the head gasket looks like new.

Any opinions? The pictures are as good as I can get.

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Looks to me that it blew into the return hole and also vented on the lower side.

Thanks to the tips from fellow veterans of this site, I went ahead and changed the head gasket. Apparently that was the problem. The leakdown test afterwards resulted in 60# inlet pressure and 50# outlet.

I used the Newry cutter on the seats and cleaned the valve faces. Lapping in the valves showed a nice seating area.

What an s o b it was to work on that reed valve! But it was something I had to check.

Glad to hear it. They aren't too bad once you get a couple under your belt. The last one I did, I had talked to the owner in 2007 that I felt he had a start of a headgasket leak. He has a couple of tractors, but 4 years before getting it fixed! BTW, if you can see the edge of the reed that it is place yet- you should be good to go. I keep a set as they are cheep, but I haven't seen a broken one.