Well that why you do lead down tests as it is none invasive and give you a good idea what is going in the cylinder without even pulling the head. Based on the results you would have a good idea where the problem lays.
Anyways since you have the head off check the valve guides for excessive wear as a worn will lead to excess oil in the cylinder and an exhaust will cause a lot of smoking but no excess oil the cylinder. Even the cylinder is not scored you should still mic it at top, middle, and bottom on the ring travel; twice at each level 90 degrees of each other. This will check for overall wear, tapering, and ovaling. I seldom see worn cylinders without worn rings. If you have less .005 of overall wear then you should re-ring with standard rings once you break the glaze.
Nath, I do see quite a bit scored cylinder in 4 cycles too. Operators thinks air filters are unnecessary at times.
Matter of fact I got a log splitter that I just did the above tests on which just be kill it as I can't oversize beyond .020 over and it has all the above problems including heavy scoring of he cylinder walls. I got fairly good idea once ridge hone the cylinder I going to go pass the .020 over before removing the scoring. Initially I had 30 psi compression and 60% leakage rate which a good portion was the intake valve seating but once I pulled the head I found the exhaust valve guide worn out and the cylinder scoring.
Too bad Briggs no longer sells the .030 over pistons and rings or the .010 over sets. There are a lot of savable engines if they did. I reckon their logic is it is worn enough to oversize you go to .020 right of the bat and if too worn to go to .020 it is a waste of time and you should just replace the engine if a replacement is available or kill off the equipment.
