Briggs & Stratton 331877-3036-G5 540cc 21.0 Gross HP Intek Engine with 1-Inch X 3-5/32-Inch Length Crankshaft Tapped 7/16-20 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 Pantented linear balancing system provides smoother performance CARB Compliant