Next step was to go after that stuck valve issue and to rebuild the carburetor. So I pulled off the hood and grill assembly:
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Found a mouse nest between the muffler and the fans, as well as leaves. Can you say FIRE?
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Carb is off. I'm 99% certain I'm going to have problems getting that linkage back together.
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Popped the cylinder head, this is a shot at the underside of it:
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You can see exhaust valve stuck open. I tapped it down with a rubber mallet, turned the crank and it stuck again. Repeated 3-4 times, and it started functioning on its own.
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Here's a look inside. The cylinder walls actually look great. The picture makes it look bad because it's reflecting the carbon on the piston:
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I started cleaning the top of the piston. This is my first time here, so I started with a rag and gas. Then I moved up to fine steel wool with gas. This is a picture of it half-cleaned. I did more and got it looking pretty good. Then I started reading and found that oven cleaner works well. I'm going to get some of that to tackle the valves.
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Here's a view of the valves. I *think* they look pretty good, but again I'm a noob on this stuff. Once I get the valves and the seats cleaned up, I'll have a better idea.
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BTW, I got tripped up on watching that exhaust valve as I spun the crank. It goes up all the way one cycle, then up just a little on the next. Then I had an "a-ha" moment when I remembered reading about the compression relief they built into these Kohlers to make starting easier. That's the little open I'm seeing, right? (edit 7/18/11 - yep, it was the compression relief)
One more pic of the underside of the head, partially cleaned:
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After I get these valves and such cleaned, clean and rebuild the carb, the new head gasket (on order) should be here in a few days. We'll put the motor back together, change the oil, and fire it up. Fingers crossed... (edit 7/18/11 - never did put it together and start it up. As you'll see later, I went on to a full rebuild)
But I won't be putting the tractor back together at that point. Next step is to pull the motor and go to work on those ISO mounts. I'm going to do the crossbar mod while I'm in there.