500cc 17.5 Gross HP Briggs & Stratton Engine with 1-Inch x 3-5/32-Inch Length Crankshaft, tapped 7-16-20. This engine features 12 volt electric start, rewind back-up start and a 9 amp DC alternator. The exhaust manifold and muffler are included but fuel tank is omitted. For use on wide area walk behind mowers and trail mowers. Emission compliant for sale in all 50-states.