Need help with a Kohler K241
 

Rebuilt k241 (oil ring stuck). now runs hot and valves will not keep their clearance. Replaced rings, gaskets, cleaned everything. ran about 30 min. then the problem started. Right after. cut grass till engine got hot then loss of power. let cool, checked clearance and it was to wide. reset ran again same thing. yesterday took head off, had carbon, cleaned, lapped valves, reset clearance. ran it and the same thing happened.

Did you follow the procedure in the FSM when adjusting valve clearance?

Followed the manual. Set the clearance. This is the second time I have rebuilt this engine. First time was in 2019. This time when I took the head off, there was oil standing on top of the piston (it used 1/2 qt of oil for 150 feet). So I took it apart and found oil rings stuck. Clean everything, new rings, gaskets, lapped the valves, and set them. It will run till it gets out, then looses power. Let cool check valve clearance and they are wrong. They lapped good, no slop, not bent.

Is it one valve that looses it's clearance or both?

How tight/loose is the adjusting screw in the tappet?

Did you remove the valves during the overhaul? Exhaust valve stems can get a thick layer of carbon and will stick causing the engine to quit. It usually happens to hydrostatic models but not limited to them.

Removed both valves, cleaned them, had no carbon build up. Lapped valves till got a good contact surface.

Did you bore and hone the clyinder in any of your rebuilds or did you just snuck in new rings only?

I'm with Billy
The kind of oil usage and carbon build up you describe sounds like your got a problem with the cylinder sealing, not a valve problem.
What is the ring end gap when checked in the cylinder?
Is the new piston you installed with the rings the proper size for the overbore? What is the piston to wall clearance? is the bore tapered/out of round when checked with a dial bore gauge?
We need to know these things to properly help you, other wise we are just looking at a muddy Crystal ball.:bigthink:

Sounds like he tried to get by on the cheap and not do a proper rebuild and is now paying the piper.

I didn't cheap on the rebuild when I did it in 2019. This time the oil rings stuck. So I did just a rings, honed the cylinder, checked ring gap within spec. Lapped valves, new gaskets after cleaning everything. The first time the machine shop bored out the cylinder .010. So all new, rings, piston, rod, valves. Everything has been working OK till this summer. Used 1/2 quart of oil for 200 feet. Took off head, oil sitting on top of piston. No marks on walls, compression rings OK, oil rings stuck. That is why I did a refresh on it.

Are the threads in the tappet stripped?

No the threads don't appear to be stripped. The bolts are tight when using the two wrenches to adjust them.