The Yamaha YFZ450 is a sport ATV (all-terrain vehicle) first introduced by Yamaha in 2004. It is powered by a 450cc single-cylinder, liquid-cooled four-stroke engine. The YFZ450 is known for its high-performance capabilities and is often used in motocross and off-road racing. It features a lightweight aluminum frame, suspension with adjustable preload, and a five-speed manual transmission. The YFZ450 has been updated over the years with various changes to the engine and suspension, but it remains a popular choice among sport ATV riders.