Briggs & Stratton 31R977-0027-G1 Vertical Intek Series Engine, 500cc, 17.5 Gross HP, 1″ x 3-5/32″ Crankshaft, 1/4″ Keyway, 7/16″-20 Drilled & Tapped, 12V Gear Drive Starter with 9 Amp Alternator, Supress Afterfire Solenoid