Robin Subaru

By Heather Burlingame, Senior Production Editor | September 28, 2010

Ex SeriesWith four models rated at 4.5, 6.0, 7.0 and 9.0 horsepower, Ex Series air-cooled engines feature a chain-driven overhead cam. The design lowers resistance for fuel/air flow, and pent-roof-type combustion chambers allow high combustion ratios for more power and torque, while reducing emissions.