Briggs & Stratton 500cc 17.5 Gross HP Engine with 1-Inch x 3-5/32-Inch Length Crankshaft Tapped 7-16-20. 31C707-0026-G1 Cast iron cylinder sleeve and dual element air filter for extended engine life Overhead valve design (OHV) for cooler operation and longer valve life Float carburetor for consistent, easy starting. Emission compliant for sale in all 50-states. Pantented linear balancing system provides smoother performance Non-CARB Compliant/Not For Sale In California