Right as Yamaha unveiled the latest YFZ450R, their factory-backed race team, Wienen Motorsports, was wrapping up its second consecutive AMA ATV MX title. In fact, the boys in blue, Chad Wienen and Thomas Brown, finished first and second, respectively. Those results also helped Yamaha capture the manufacturer’s title, followed by Honda, Can-Am and Suzuki. The riders are competing on modified versions of the only machine in its class that has seen significant changes in recent years.
In stock trim, the aluminum-framed YFZ450R uses Yamaha’s latest DOHC, liquid-cooled, four-valve, 499cc, four-stroke engine. This year, Yamaha made some minor changes to this powerplant. Up top, they increased the compression ratio slightly from 11.6:1 to 11.8:1 and revised the cam profiles and ECU settings to offset a clean-air device called the “Air Induction System,” which they had to add to this and all machines in the near future. The Grizzly now is equipped with the AIS system as well. Most manufacturers’ street-bike lines have been using AIS for years, and it’s not a big deal to remove if you have your sights set on closed-course racing. It’s basically a small tube that flows cool air into the exhaust port of the head to make sure fuel is completely burnt as it enters the exhaust system.
What is more noticeable in the drivetrain is the addition of a slipper-style clutch. Even with the engine not running, you can feel its advantages of a lighter clutch pull. The system operates only using three springs instead of the standard six. When the machine is running, clutch engagement is super smooth and predictable. The clutch really shows its advantages when you come into a corner fast and have to downshift to set up for the exit. This clutch reduces engine braking noticeably, keeping the rear tires rolling and avoiding stalls. Furthermore, if you are braking hard on a downhill, the rear tires don’t tend to lock up or squat, so the suspension works better at reducing braking bump kick that we don’t want when racing down a hill. This feature will help novice through expert racers on the track, as well as riders on the trails. A new throttle body also brings a lighter thumb-throttle feel and allows for idle speed adjustments.
Even with the stock muffler still mounted up, the YFZ450R is fast. We could ride the track with enough confidence to hit the double jumps and clear the step-ups without worry. It has great torque down low for getting out of the corners and can be revved without any noticeable flat spots. Throttle response is quick and crisp. If we were to enter a race, though, we would invest in a GYTR or other aftermarket slip-on muffler. The weight savings and power increase would almost guarantee a holeshot.

Along with the power improvements Yamaha made to the YFZ450R this year, a brand-new body, new tires and shocks make up the new ride. In passing, the bodywork doesn’t look a whole different, but it is. Yamaha moved the front fenders forward slightly and flattened out the rear fenders to be more inline with the back of the seat. Both changes were noticeable to our testers as they jockeyed back and fourth around corners. Even if you are a 6-foot-6 rider, you won’t hit your knees on the fenders. The bodywork was also reshaped, so any-sized rider could slide their knees smoother when transitioning from the frame to the bodywork in the center of the machine.
All of these changes also increased the logo or graphic area for racers wanting a better billboard to display sponsors. Also new for this year, the quick-release bodywork fasteners, found only on previous SE models, are used on the base-model unit. This allows you to easily remove or install the entire body, except the radiator scoops, without tools in about two minutes. More handling improvements were added to the list in the form of new Maxxis tires. The new meats don’t look a lot different than the Dunlops that were on last year’s model, but on the track, you can easily feel their benefits. Yamaha still equips the YFZ450R with trail- or track-ready tire sizes of 20×10-9 in the rear and 21×7-10 up front. The sizing is typical of most trail quads, but a bit tall for serious track riding. Most track quads run 18-inch rear tires and 20-inch tires up front. However, we have found Yamaha didn’t make a bad choice here. The taller sizing still allows the YFZ450R to corner like it’s on rails. Yes, you don’t feel as close to the ground as on, say, a Suzuki LT-R450 or KTM 450SX, but bump absorption is better, and you never get hung up in rutted corners.
In fact, we find you can get a better jump off of the starting line with a taller, slightly rear tire. We will show you some lap-time differences using these tall tires versus lower-profile tires in the near future. These Maxxis tires do slide predictably and grab traction when exiting out of the corner just about as well as any aftermarket MX tire.
Off the track, the stock tires perform just as well. They help provide 9.3 inches of ground clearance below the engine and over 4 inches of clearance under the rear sprocket and brake rotor. Yamaha installed top-of-the-line, super-slick, Kashima-coated shocks both front and rear. They are fully adjustable and rebuildable. Up front, 9.8 inches of wheel travel is found, and a full 11 inches of travel is found at the rear end.
Over the bumps, this Yamaha is more suited for an aggressive rider. It’s set up a bit on the stiff side, which helps reduce body roll in the corners and definitely soaks up flat landings or cased jumps well. There is plenty of high-/low-speed compression adjustments available, however, if you are not attacking the track hard or prefer a smoother ride on the trails. In both cases we liked the high-speed compression clickers turned a few clicks softer than stock.

All these improvements did come with a $200-higher price tag for 2014 at $8799. When you compare that to around $8000 for the steel-framed, carbureted Honda 450 or $8299 for the EFI, aluminum-framed Kawasaki KFX450, the investment is not much greater. While still great machines, neither sit at 50 inches wide like the Yamaha and neither have changed significantly in five years-although we do like the fact that the Kawasaki has reverse.
We are glad Yamaha is still investing in the sport quad market. They see the sales numbers starting to rise and are taking notice. We hope Honda, Kawasaki and Suzuki follow suit and join Yamaha on the track and trail with new models of all sizes soon. If not, we will still be happy charging the trails and turning laps on the 2014 Yamaha YFZ450R.

Engine …  DOHC, liquid-cooled,
      5-valve, 4-stroke
Displacement  … 449cc
Fuel system … Single 42mm EFI
Transmission … 5-speed manual w/
      no rev
Suspension/wheel travel:
  Front … Dual A-arms/9.8″
  Rear … Swingarm/11″
  Front … 21×7-10
  Rear … 20×10-9
Length/width/height … 70.7″/48.8″/41.9″
Wheelbase  … 50″
Fuel capacity … 2.6 gal.
Ground clearance … 4″
Claimed wet weight … 405 lb.
Colors  … White/blue, white/orange,
      red (SE)
Price … $8799
Contact … www.yamahamotorsports.com

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