The YFZ450R’s engine gets some attention to make it the most powerful 450R mill to date. The compression ratio has been bumped to 11.8:1 via a longer connecting rod rather than a new piston shape, so in essence it is a quarter of a millimeter stroke-job. Valve lift has increased with new intake and exhaust cams, and the ECU has been remapped to make use of the mechanical changes. Additionally, a 12-hole injector feeds a new 42mm Mikuni throttle body for better response at all rpms.
In an industry first Yamaha has fitted an assist and slipper clutch in an ATV. Using engagement ramps to apply greater pressure on the clutch plates during acceleration allows for lighter springs and results in a 25% lighter pull at the lever while still guaranteeing positive engagement. More importantly, on deceleration the ramp slightly separates the plates to allow some slip to keep the rear wheels from skipping or sliding when coming into corners. This also fights rear suspension lock-up from engine braking forces.
The YFZ’s front shocks are now 3mm longer with an optimized suspension setting to utilize the character of the new Maxxis tires developed for this model. Yamaha claims these new tires have a lighter steering feel with more precise handling. The rear tires have better bump absorption and more predictable sliding. The wheels also got a change with an inward rolled lip to increase rigidity.
The bodywork on the YFZ450R received some serious attention from Yamaha’s designers to improve the ergonomics, not only in terms of comfort but also for body positioning at race pace. The front fenders have been moved forward 30mm and lowered 10mm to give the rider more room for their knees in the corners. The tank area plastic now covers more of the frame for better durability and reduces the chance of catching knee braces on the plastic. A flatter rear fender area allows the rider to slide from side to side unencumbered. The foot wells have also been opened up to accommodate riders that ride on the balls for their feet and need more heel room. Yamaha has also fitted the bodywork with quick release fasteners for tool free removal.
The 2014 Yamaha YFZ450R has a MSRP of $8,799 in Team Yamaha Blue/White and Blaze Orange/White colorways. There will be an SE version available as well, which will demand a $200 premium.