I don't know what you have for a Kohler engine so these are only guesses as to what you have for a engine and wire color. This is for a Kohler Command. You should have three wires going to the voltage regulator. The two outside white wires go to the stator under the flywheel. This test should be done at wide open throttle. You should be getting around 25 or more AC voltage at these two white wires and if not you have a stator problem. Now if that checks out OK check the center green wire in which you should be getting around 13.5 or more DC voltage. If not you have a bad voltage regulator. This is how you check your voltage regulator.