For 2014, Yamaha has upgraded its YZ450F by increasing horsepower and optimizing the dirt bike’s chassis.Starting without the 449.7cc engine, Yamaha completely revised the top end (piston, intake and exhaust valves, and ports, valve mechanism, ignition timing, and fuel injection mapping) for better performance throughout the powerband. Yamaha also revamped the bike’s ECU.As for the chassis, Yamaha added a newly-designed, aluminum Bilateral Beam frame. The head pipe on the new frame is moved 10mm closer to the rider, though the overall dimensions are about the same as the 2013 YZ450F.This gives the YZ450F a new compact chassis that provides the most instinctive handling in the 450 motocross class, Yamaha says.Attached above is a photo gallery of the 2014 Yamaha YZ450F, which features 20 images that also make for great wallpaper. To download as wallpaper, click the desired thumbnail to expand. Right click on the image and Set as Desktop Background.For a preview of the 2014 Yamaha YZ450F, including all features and specs, click here.