Mounting holes are not threaded. Use your existing bolts from your old engine, as the manufacturers use self-threading bolts upon installation. This genuine 540cc Briggs & Stratton single cylinder engine offers dependable power for your equipment needs. With a power rating of 19 horsepower, this engine features a premium Dual Clean air filtration system, electric starter, and maintenance-free Magnetron electronic ignition. With a manufacturer limited warranty of 2 years consumer use / 1 year commercial use, Briggs & Stratton provides power that you can trust. This engine includes a Dura-Bore cast iron cylinder sleeve for extended life. This engine includes an installed muffler. This engine includes a 9 amp charging system.