Small Engines (Lawn Mowers, etc.): sear tractor engine # cv15s-41567 Kohler 15.5hp, crankcase breather, valve clearance

Question
Recently replaced stator, flywheel,and some misc. parts and the tractor ran fine for about 3 wks. It has always spit some gas out of the when starting. Yesterday I started it and it spit an excessive amount out. As it was running it seemed as though the engine was bogged down and when I engaged the cutting blades the problem got worse to the point the tractor was moving slowly and wanting to cut out.

Answer
The first thing I would check would be valve clearance.  Be sure the intake valve is closing all the way.  The next thing to check is the crankcase breather to be sure it is not full of oil.  If you have a lot of spit back to also have a plug muffler or a muffler with a broken baffle.  My guess is valve clearance.