I've always been an avid fan of all aspects and disciplines of ATV riding and racing, but the core of my being requires regular doses of the woods-warrior style of riding. Maybe it's due to the fact that I was born and raised in the Southeast where the hilly and even mountainous terrains are littered with the ambient green of tightly nestled trees throughout the landscape. Regardless of the reason, there aren't too many things that I enjoy more than my addiction of dancing a finely tuned quad through the tight, winding, and technical trails of my region. Yamaha has recently further fed that need with yet another new intuitive quad designed specifically for this scenario: the YFZ450X.
Last year Yamaha released an innovative and newly designed YFZ450R to the already best-selling sport 450 lineup on the market. After our initial impression and long-term testing, the new YFZ450R was well received by everyone on our staff. Due to its wider MX-styled stance that equals near 50 inches wide, I must admit that I was a bit concerned that the woods warriors, which is nearly 50 percent of the market, would be left out from the great new innovations the new R had to offer. But behind the scenes Yamaha was already at work developing the YFZ450X, a version that would satisfy anyone who seeks the high-speed thrill of tight technical trails.
Since the YFZ450X is based off of last year's YFZ450R with a few tweaks and configuration changes, I figured a quick recap on the new generation of YFZs was in order. Starting with the frame, Yamaha engineers designed a weldless aluminum frame to keep things light, with a steel bottom that allows the engine to sit low. The new V-shaped frame is designed with A-arm mounting points that allow for more suspension travel and are stocked with fully adjustable shocks that have a Kashima coating to keep the oil inside at a lower temperature. The new 449cc engine makes use of titanium five-valve cylinder head technology and a camshaft that maximizes the torque available in the low and mid ranges. The crankcase in this new engine holds a crankshaft that better handles the increased balance ratio along with a counterbalancer that helps keep annoying vibrations to a minimum. This crankcase was also created to house the oil tank, which not only centralizes mass for improved handling, but also makes changing the oil quicker and easier.
One of the most exciting innovations for the new generation of YFZ is the method in which fuel is delivered to the engine. The Yamaha Fuel Injection system that was incorporated makes use of a 42mm Mikuni throttle body and 12-hole injector which helps to create a more linear type of power delivery and provides an atomized fuel delivery for enhancing the engine's overall performance. Among all of these major new improvements, there were also great benefits such as a T-shape designed seat, a four-position-adjustable ProTaper oversize handlebar, a redesigned thumb throttle, and an easy-to-remove body design that does not require the removal of the battery. Nearly every inch of the YFZ had been redesigned to best suit the needs of performance riders.
What's New On The X?
Yamaha's first and most likely update to the X model was in the form of narrowing its width by 2.7 inches from the YFZ450R's 48.8 inches. The X model is 46.1 inches wide, the same width as the former YFZ450 as well as a 50mm shorter axle than what comes on the 450R. This new quad comes with a redesigned front suspension system. The front A-arms are shortened by 43.9 mm to 395.2 mm and have a change in caster from 5 to 4 degrees, which should allow for easier steering and less feedback in the bar. The KYB shocks are now 426 mm long (from the 450R's 462mm length) and possess easy-to-adjust damping. These new 9.4-inch Kashima-coated piggyback shocks are 28mm longer, 8mm bigger in diameter, and have a 2mm longer stroke while still offering high- and low-speed compression, rebound and preload adjustment.