Jim, the engine is completely stock as far as I can tell. I never seen another one of these machines on the road, but in comparison to the manual, everything is there the way it should be, although I can't comment on the jets in the carb, those might be different.
My best guess at this is that the engine is overheating because of bad mixture, or the wrong kind of plug is in there which can't handle the heat. I have no idea if plugs fail, but I had a spark tested on this one and the spark just started dissapearing. I don't know if too much heat cuses the spark plug to fail, I got a colder plug and I will try it out.
The oil temp light never came on the machine, so I'm guessing that the engine never did reach a temp where it would self destruct, however the manual does state that plug selection is rather critical for air cooled engines. Again, no mention of what happens if a bad plug is selected.
If it's none of these items, then I guess the cylinder and piston are shot, and they have to be overhauled. I have no problem with that, but first I want to be sure that this is indeed the problem. I'm taking my compression tester up north this weekend, I will hook it up and see what it tells me.
I have to look into getting a leakdown tester and a valve spring compressor.
Looks like I got me a lemon.... but other then that, this thing is really great for chores around the cottage.
Thanks much every and keep the suggestoins coming, even if you have a hunch you might know what causes this.
I have yet to meet a spark plug pro
xp