Small Engines (Lawn Mowers, etc.): kohler command problem, kohler engines, lifters

Question
HI, I have a Kohler 16 hp ohv command engine that wont run.  The engine is backfiring like it is out of time.  I checked the flywheel key and its fine.  I was wandering if you think it is in the valves.  I have not had much experience with kohler engines.  Can you adjust the valves and if so do you know the clearances. I was leaning toward valve trouble or could it be the ignition?

Answer
This engine has a problem with sheared flywheel keys. Start there. Hydralic lifters so the valves aren't adjustable.  To have a backfire you have to have a valve open when the plug ignites the fuel.  This can only be caused by a valve not closing or a flywheel key being sheared and throwing the engine out of time.

Common.