Briggs & Stratton 31L777-3136-G5 vertical Professional Series engine is 500cc and puts out 17.5 HP (gross horsepower). This single cylinder engine has a 1″ x 3-5/32″ crankshaft and features a 12V electric starter with 9A alternator, a fuel pump, an oil pump with filter and a muffler. Briggs & Stratton Professional Series engines feature full pressure lubrication along with oil and fuel filters for a longer life with less maintenance. Chrome plated valves and advanced air filtration provide maximum protection. This engine is for use on lawn mowers. Buyer protection package provides a two-year limited consumer engine warranty. 50-State CARB Compliant. All engines purchased from us ship for free and are foam packed for added protection during transit.