If you're into ATVs that go fast-no scratch that, really fast-then you may want to take a look at Yamaha's new YFZ450R. Yamaha's goal was to build the world's best all-around high-performance racing and recreational sport ATV, and this is what they came up with.
It's powered by a rompin' fuel-injected 449cc five-valve DOHC liquid-cooled single-cylinder engine. This engine uses the cylinder head and cylinder from the championship-winning YFZ450F. Yamaha says it has camshafts designed just for this machine that hammer out superior low- to mid-range torque and push through to a high-revving, hole-shot grabbing top end. Gotta love that description. The engine is also equipped with electronic fuel injection featuring a 42mm Mikuni throttle body, a 12-hole Denso injector system, and a Mitsubishi 32-bit ECU. The sum of which is exceptional atomization of the fuel for maximum power, unrivaled throttle response, and automatic altitude and temperature adjustment.
The core of the machine is an all-new aluminum frame for light weight. Yamaha didn't use aluminum under the engine though. Instead they used a frame member made from tensioned steel for its combination of strength and thinness. This allowed the designers to sit the engine lower overall for what they call "excellent mass centralization." Translated, this setup helps create unmatched handling.
 Fuel-injected with five valves,...  Fuel-injected with five valves, the single-cylinder DOHC 440cc four-stroke engine is a powerhouse. |  The front suspension has long...  The front suspension has long A-arms, KYB piggyback shocks, and 9.8 inches of travel. | |
Another noteworthy area of the YFZ450R is the suspension. Up front it uses long A-arms and 44mm KYB piggyback shocks. These shocks have a Kashima coating for smooth operation with superb bump absorption and excellent anti-bottoming characteristics. The front suspension offers an impressive 9.8 inches of travel. Also noteworthy up front is the fact that the front frame is noticeably narrow at the A-arm mounting points. Yamaha says that this dramatically reduces changes in camber as the long A-arms travel through their full range of motion. The rear suspension utilizes a swing arm that is crafted from strong, gravity-fed aluminum, and it's matched to a fully adjustable 46mm KYB piggyback shock absorber for excellent handling. Get this: rear wheel travel is an outstanding 11 inches.
Other cool stuff: An all-new throttle lever that requires less effort resulting in less fatigue; an LED panel on the fender shows low fuel, coolant temperature, check engine, and neutral gear; dual front hydraulic disc brakes and a lightweight wave-type rear rotor; newly-designed Dunlop front tires; ProTaper handlebars; wide 65mm foot pegs; and wide motocross-spec wheels.
So there you have it. In 2003 Yamaha announced the original YFZ450 as the first race-ready 450-class ATV and they're continuing that legacy with the '09 YFZ450R
Specificationas
General
Vehicle model: 2009 Yamaha YFZ450R
Base price: $7,999
Colors: Team Yamaha Blue/White, White/Red
Engine
Type: Liquid-cooled with fan DOHC four-stroke single
Displacement (cc): 449
Bore and stroke (mm): 95 x 63.4
Drivetrain
Transmission: Five-speed manual clutch
Final drive: Chain
Suspension
Front: Independent double-wishbone, Kashima-coated piggyback shocks with high/low speed compression, rebound, and threaded preload adjustments, 9.8 inches of travel
Rear: Cast-aluminum swing arm, piggyback high/low speed compression, rebound, and threaded preload adjustment, 11.0 inches of travel
Brakes
Front: Dual ventilated hydraulic discs, twin-piston calipers
Rear: Wave-style ventilated hydraulic disc, twin-piston calipers
Tires
Front: AT21x7-10 Radial
Rear: AT20x10-9 Radial
Dimensions/Capacities
Weight (lb): 405 (wet)
Length (in): 70.7
Width (in): 48.8
Height (in): 41.9
Seat height (in): 31.9
Ground Clearance (in): 4.5
Fuel capacity (gal): 2.6
Wheelbase (in): 50.0