My tractor's engine runs good, it doesn't backfire, the timing is good, it generates enough power, doesn't knock or anything, doesn't leak oil (but i did notice drops of something on the floor near the front of the tractor when pushing it around, possibly fuel?), it hopefully doesn't burn oil, and it only smokes because the fuel soaked through the rings before I put the fuel shutoff on. Other than the fact that's it's super inconsistent, it's a solid tractor for something we got for free.
Tractor Info:
MTD Powr kraft (1996, not a 1994) 46" cut, 18hp Briggs opposed twin, hydrostatic drive
I don't have any other info at the moment. Well, I do, but my computer won't load the pictures.