DAVE - There's instructions in the Kohler manual about making a "U-tube manometer. You need 3-4 feet of 1/4" clear tubing, a small chunk of wood, say a 1X4 a foot long, and some sort of stopper, cork, etc.
Push a rigid tube (steel) thru the stopper that seals off the dipstick tube, hook the one end of the clear tubing to the stopper, and fasten the other end in the shape of a "U" to the board and draw lines every inch. Fill the clear tube with water so the "U" shape is HALF FULL, you could color it if you want, Start engine, forget what speed to run the engine, say a fast idle. Stick stopper or cork in the dipstick tube and note how far apart the two top levels of the water in the bottom of the "U" are apart.
Tests the condition of the check(reed)valve on the breather, ring seal. Works great on K-series. Tried it on my buddy's KT17 in an off-topic tractor and almost sucked ALL the water out of the clear tube into the crankcase, so Be CAREFUL. Needless to say, if the opposite happens, you blow all the water out of the tube the engine doesn't pass the test. ;-)