The Big Dog K9 is a custom-built motorcycle designed by Big Dog Motorcycles. It features a 113-cubic-inch (1854 cc) S&S air-cooled V-Twin engine that produces 113 horsepower and 130 lb-ft of torque. The K9 also features a five-speed Baker transmission, a six-gallon fuel tank, an adjustable suspension, and brakes with both front and rear disc brakes.