We had been getting the same questions for quite some time: "Have you guys heard that they're testing a new Yamaha sport quad somewhere near San Diego?" or "Have you heard anything about the new Yamaha sport quad with the WR450F dirt bike engine in it?" Well, now we can finally pass the real scoop along to you!
Engine
To answer the most burning question--the new YFZ450 houses a hybrid combination of the ultrapowerful, five-valve WR450F and YZ450F dirt bike engines. More specifically, the quad's 439cc engine employs the same dual-overhead cams, titanium valves, intake cam, ceramic-coated aluminum cylinder and ratchet-type shifter found in the YZ450F; the exhaust cam (with auto-decompression) was borrowed from the WR450F. As you can see, the engine used in the quad is more race than sport.
A newly designed 11.9:1-compression, forged piston requires the machine to run on premium unleaded gas. Speaking of gas, the new YFZ450 quad breathes through a downdraft Keihin FCR39 carburetor (used for the first time in an ATV). The all-new, close-ratio five-speed transmission features a gear ratio not found on either dirt bike--it has been optimized for the ATV specifically. Other features include a lightweight magnesium valve cover and a quick-access magnesium clutch cover (both courtesy of the YZ450F) which hides new, thicker clutch plates (1.6mm versus the bike's 1.2mm).
Suspension
The YFZ wears compression/rebound/preload-adjustable shocks both front and rear (Kayaba shocks up front with a Showa rear shock). The front Kayabas come with aluminum piggyback reservoirs and nitrogen-filled bodies, and the rear Showa is similarly equipped.
The front suspension is unique in the fact that it uses a set of lightweight aluminum upper A-arms with standard steel tube lower arms. Note the sweep to the lower A-arms to accommodate the long-travel (9.1 inches) front shocks. The rear Showa is mated to a YZ450F-style linkage setup. The shock connects to a lightweight, cast-aluminum, anti-squat-design swingarm to help reduce unsprung weight.
Tires
Another clue that this machine is more performance-oriented than any previous Yamaha quad is its tires. The fronts are new 21x7-10 Dunlop meat (they're actually modified versions of Raptor tires with stiffer sidewalls). The rear 20x10-9 tires feature an all-new tread design. This tread pattern is more suited for MX track conditions than the average sport-spec tire standard on most sport quads.
Protection
Light, compact composite skid plates guard the engine and swingarm.
Race Features
Last, but not least, are the YFZ's more race-oriented features:
YZ-style adjustable brake and clutch levers: Both the brake and clutch can be adjusted without a tool (via a thumbwheel), and the primary lever is also adjustable.
Easily removable parking brake: Although Yamaha doesn't condone taking off the parking brake, most racers will jettison this item almost immediately. Luckily, all it requires is the removal of two bolts and popping the lever off!
Racer ergonomics: Yamaha was quick to point out that the YFZ's front fenders have been positioned slightly farther forward than on a typical sport machine to allow riders more room to hang off the side for aggressive cornering. In addition, the seat has been shaped accordingly to match the plastic positioning (the machine has a low 31.5-inch seat height).
Weight: How does a 350-pound dry weight sound? That's 22 pounds less than a Suzuki Z400 and a whopping 65 pounds lighter than a Polaris Predator! Maybe it has something to do with the YFZ's aluminum upper A-arms as well as cast-aluminum wheel hubs, swingarm, subframe and wheels. And don't forget that high-tech engine is completely decked out with a host of titanium, magnesium and aluminum lightweight goodies!
GYT-R accessories: The biggest bolt-on that blew us away is the accessory kickstarter kit for the YFZ! Yes, with a minimal amount of work, you can drop the electric starter and its weight for a smooth-looking billet kickstarter. Other accessories include a performance-oriented +1-inch A-arm and +2-inch-wider axle, exhaust kits, nerf bars, billet-aluminum shifter and brake pedals, aluminum grab bars and skid plates.
Price: MSRP is "under $7000," but we're guessing that means $6999.
Yamaha YFZ450
Retail Price: $NA (under $7000)
Engine
Type: Single-cylinder, four-stroke, DOHC
Displacement: 439cc
Cooling: Liquid-cooled with fan assist
Carburetion: Keihin FCR 39mm with TPS
Lubrication: Dry sump
Ignition: CDI
Starting: Electric
Drivetrain
Drive System: Chain, 2x4
Transmission: 5-speed manual
Suspension (Type/Travel)
Front: Dual A-arms/9.1 in.
Rear: Swingarm/10.1 in.
Tires
Front: 21x7-10; rear: 20x10-9
Brakes
Front: Dual twin-piston discs; rear: disc
Dimensions
Wheelbase: 50.4 in.
Claimed Dry Weight: 350 lb
Ground Clearance: 4.4 in.
Length/Width/Height: 72.4/46.1/42.9 in.
Seat Height: 31.5 in.
Fuel Capacity: 2.6 gal.
Electrical
Taillight: Yes, with brakelight
Headlight: Dual 30-watt Krypton multireflector with high/low beam
Instrumentation: Neutral, high-temperature indicators
Colors: Blue, white