Small Wonder Small in size, but big in performance, the F2.5, single cylinder, four-stroke engine provides an extremely lightweight and portable engine for smaller craft. This versatile and compact unit includes a handy carry handle making moving and installing this engine effortless, while the smart leak-free design allows the engine to be safely and conveniently stored on its front, right or left side. With its new stylish round cowling, improved combustion efficiency and lower emissions output, the F2.5 not only looks great, but delivers Yamaha’s legendary reliability, fuel efficiency and smooth running performance.