We have been contacted by several lawn mower racer guys wanting a quality machined, lightweight, ring gear acceptable flywheel for the Kohler V-twin engine. We used our computer software in designing this flywheel and have developed the lightest highest quality machined flywheel on the market today. Our ring gear flywheel with the cooling fan, hardware and the stock ring gear weighs only 6lbs 12oz. The flywheel features the stock 1.875 centering pilot and the factory 4 bolt pattern for aux drive options. Flywheel is to be used with your stock steel ring gear.