In this episode of Highside/Lowside, Zack & Spurg welcome back Patrick Garvin! The trio embark on the ambitious task to design the Mount Rushmore of motorcycle engines. First up - Touring motorcycles! Which engine deserves this prestigious honor? Check out more from RevZilla: Common Tread): News, opinions, and written reviews RevZillaTV): Bike reviews, How-To's, and product videos