The Yamaha YFZ450 is a high-performance, four-stroke ATV(All-Terrain Vehicle). Introduced in 2003 as a 2004 model, it was a huge leap forward relative to its competition. It uses many light-weight materials to give it the lowest dry-weight (350 lbs.) of any 450-class sport ATV. Overall, it is a very capable ATV, with good handling, braking, and overall performance.

This ATV was considered "revolutionary" and the "biggest step toward an off the showroom floor race ready ATV available by any the four major Japanese manufactures". By the end of the 2004 ATV racing season, two of the three National Championships were claimed by riders riding the Yamaha YFZ450: Keith Little, Clint and Bill Ballance.^[1]

General

The Yamaha YFZ450 is a comfortable bike. For an ATV, it is very narrow, designed with the rider in mind. On the front, the fender is moved forward so that tall riders can fit themselves on it nicely. The acceleration and handling is all very smooth, as expected from a Yamaha ATV.^[2]

Yamaha claims that the 2007 edition of the YFZ450 is the "lightest, most powerful ATV ever, winner of just about every magazine shootout". It comes standard with a pushbutton electric starter and a flip-type parking brake. New change for the 2007 model include an aluminum handlebar, redisgned front master brake cylinder, drilled rear disc brake, and an internal oil jet. These features boost handling, braking, and improve the ride of the ATV.^[3]

A few simple modifications can be made to increase power. Removing the air-box lid, as well as the baffle and spark arrestor from the exhaust pipe will improve the air flow into and out of the motor. Another popular modification is to retard the exhaust cam one tooth, giving it the same cam timing as the YF450F dirt bike. These changes together with the appropriate carburetor adjustments are practically free and result in a significant power increase.

Since its introduction in late 2003, the Yamaha YFZ450 has seen a massive explosion in after market parts. Many manufactures were quick to launch exhaust pipes, suspension parts, and body work. Some of these parts are said to increase horsepower and performance! ^[4]

It is interesting to note that while Yamaha tends to share naming structures amongst similar products (the YZ-series dirt bikes for example), the only other Yamaha product to carry the YFZ designation is the legendary Banshee (known as the YFZ350 in Yamaha part catalogs and manuals).

Model Year Changes

The YFZ450 model as a whole has not changed much; however, many small changes have been made throughout its run.

2004

• First model-year, introduced all-new

2005

• Head de-compression plug eliminated

2006

• New crankshaft with increased stroke to 63.4mm (up from 62.0mm. This made it a true 449cc. Previously a 439cc engine
• Larger capacity radiator
• Titanium heat-shield
• Longer steering stem, revised handlebars, and thicker padding in seat
• Aluminum rear grab-bar replaces steel design
• Aluminum front bumper to replace steel design
• Replaced the twin-row bearing carrier swingarm with a round-housing swingarm which made adjusting the chain easier
• Twin-piston rear brake caliper
• LED taillight
• Revised head design (very slight difference, parts interchangeable among all years)
• Revised carburetion, and ignition timing
• New tire design
• Longer travel rear shock
• New front suspension settings

2007

• ProTaper aluminum handlebars
• Revised front brake master cylinder and lever
• Drilled rear brake disc
• Internal oil jet to lubricate piston bottom
• Improved clutch

Specifications (2007)

MSRP

• $6,999 (Base Model)
• $7,449 (Special Edition)
• $7,599 (Bill Ballance Edition)

Engine

• Type: 449cc, 4-Stroke Single, Liquid Cooled w/ Fan, Titanium 5-Valve DOHC
• Bore: x Stroke 95mm x 63.4mm
• Compression Ratio: 11.4:1
• Carburetion: Keihin 39mm FCR w/ Throttle Position Sensor
• Ignition: DC - CDI
• Starting System: Electric
• Transmission: 5-Speed Manual Clutch
• Drive Train: 2WD; Sealed O-Ring Chain

Bold text The compression ratio is a single number that can be used to predict the performance of any engine (such as an internal-combustion engine or a Stirling Engine). ... Ignition occurs when the heat produced by a reaction becomes sufficient to sustain the reaction, whether it be a fire, an explosion, or nuclear fusion. ... “Gearbox” redirects here. ...

Chassis

• Suspension: Front: Independent Double Wishbone, 9.1” w/ Rebound, Compression and Threaded Preload Adjustment
• Suspension: Rear: Cast Aluminum Swing Arm, 10.1” w/ Rebound, Compression and Threaded Preload Adjustment
• Brakes: Front: Dual Hydraulic Disc, Twin Piston
• Brakes: Rear: Hydraulic Disc
• Tires: Front: AT21 x 7-10 Radial
• Tires: Rear: AT20 x 10-9 Radial

The front suspension components of a Ford Model T. Suspension is the term given to the system of springs, shock absorbers and linkages that connects a vehicle to its wheels. ... For the type of ferns known as brakes, see brake (fern). ... Tires may refer to: the plural of tire the Italian name for Tiers, Italy, a town in South Tyrol, Italy Category: ...

Dimensions

• Length x Width x Height: 72.4” x 46.1” x 42.9”
• Seat Height: 31.5”
• Wheelbase: 50.4”
• Ground Clearance: 4.4”
• Fuel Capacity: 2.6 Gallons
• Dry Weight: 350 Pounds

For other uses, see Fuel (disambiguation). ...

Other

• Lighting: Dual 30W Krypton Multi-reflector Headlights & 21/5W Brake light
• Colors: Team Yamaha Blue/White; White/gray; Yellow/Black (Special Edition)
• Warranty: 6 Month (Limited Factory Warranty)

References

1. ^ ATVRiders.com
2. ^ ATV OffRoad.com
3. ^ Yamaha's Official Website - YFZ450
4. ^ Reviews of Performance Parts