The 2014 Yamaha YZ450F is the most improved 450cc motocross bike of the year. Not only did Yamaha fix most of the bike’s previous flaws, but the YZ450F has three character traits that no other machine can touch. (1) Yamaha’s SSS suspension is head and shoulders above the other offerings. It has good damping, reasonable seal life and the proper spring rates. ( 2) The YZ450F is bulletproof. It can take a licking and keep on ticking. ( 3) The engine kicks out the jams with a very effective powerband that reaches across the rpm range with dynamic power. The previous YZ450F powerband was not very well integrated. It came in segments that didn’t mesh well with the rpm range above or below the one you were in. The new powerband is seamless. It is fast and feels faster. The coolest thing about the 2014 YZ450F powerband is that it has the most horsepower of any 450cc motocross bike ever tested, yet it delivers that power in a very gentle way (except for the irritating bark off the bottom). HORSEPOWER? 58. 24 horsepower at 9900 rpm. DOWNSIDES? If we could have sat in on the design meetings for the 2014 Yamaha YZ450F, we would have suggested that they richen up the fuel map, advance the timing and change the gearing. We also would have worked harder to get the looseness out of the front end at tip-in, reconfigured the gearbox ratios, and tried a skosh harder to get some girth out of the airbox region. Nevertheless, we applaud the Yamaha engineers for their fabulous suspension settings, broad and powerful (albeit lean) powerband, and the incredible durability of the components. The improvements are quantum leaps in a year that saw only incremental changes from the competition. Compared to the previous Yamaha YZ450F, “You’ve come a long way, baby.” THE WORD? Great powerband, superb suspension and bulletproof reliability.