Engine
Engine Type DOHC 4-stroke; 5 titanium valves
Displacement 449cc
Bore x Stroke 95.0mm x 63.4mm
Engine Cooling Liquid
Fuel System Yamaha Fuel injection (YFI), 42mm
Starting System Electric
Chassis
Front Suspension Independent double wishbone w/Kashima 

coated piggyback shocks; high/low speed compression, rebound 

and threaded preload adjustment
Front Travel 9.8 in.
Front Brake Type Dual hydraulic disc
Front Tires AT21 x 7-10 Maxxis?
Rear Travel 11 in.
Rear Suspension Cast aluminum swingarm w/piggyback shocks; 

high/low speed compression, rebound and threaded preload 

adjustment
Rear Brake Type Wave-style hydraulic disc
Rear Tires AT20 x 10-9 Maxxis?
Dimensions/Capacities
Dry Weight Curb Weight: 405 lb.
Fuel Capacity 2.6 gal.
Ground Clearance 9.3 in.
Machine Dimensions (LxWxH) 70.7 in. x 48.8 in. x 41.9 in.
Wheelbase 50.0 in.
Drive Train
Drive Train 2WD
Final Drive O-ring chain
Transmission 5-speed; assist and slipper clutch
General
Lighting Dual 30W Krypton headlights and LED brake 

light

Top Features

    Race-Ready Engine: The YFZ450R is the most technologically 

advanced sport ATV on the market today. It is simply the top 

of the line " racing" level Sport ATV. It combines a high-tech, 

quick-revving, titanium five-valve, 449cc fuel-injected engine 

with a lightweight, professional-caliber cast aluminum/steel 

chassis. The power/chassis combination will make for a 

championship-winning machine time and time again.
    Advanced Frame: The YFZ450R is motocross ready. The 

weldless frame is designed from lightweight aluminum, with a 

tension-steel bottom frame that lets the engine sit lower for 

excellent mass centralization. Suspension components and 

settings reduce weight while providing light, sharp handling 

and rider comfort.
    Aggressive SE Style: Bodywork is designed for great 

ergonomics and rider comfort, with more room to hang off in 

the corners, and the seat shape is padded in just the right 

places to improve lap times. Body panels come off easily 

without tools for service, and a dealer-installed GYTR? grab 

bar highlights the unique SE graphics package.
    Advanced Cylinder Head: The 449cc engine uses titanium 

five-valve cylinder head technology designed to deliver 

abundant power in the mid-range to top end, with more " hit"  

feeling right off idle. The higher compression ratio further 

improves overall engine performance.
    Fuel Injection: The YFZ450R incorporates Yamaha Fuel 

Injection for precise fuel delivery. With a big 42mm Mikuni? 

throttle body and 12-hole injector, this system provides 

exceptional atomization of the fuel for maximum power. The 

system also includes ISC (Idle Speed Control) for easy, 

reliable start-up and warming.
    Assist and Slipper Clutch: The industry's first assist and 

slipper clutch on a Sport ATV reduces clutch lever effort by 

about 25% for less fatigue while at the same time increasing 

clutch plate pressure for positive engagement. Additionally, 

this new clutch system reduces the engine braking effect, 

which allows faster cornering, particularly when downshifting, 

and also allows the suspension to absorb bumps better during 

braking.

Engine Features

    Powerful Motor: The fuel-injected 449cc engine has superb 

power characteristics. Power delivery is smooth and strong off 

the line with lots of midrange to top-end power.
    Compact Counterbalanced Engine: The crankcase holds a 

crankshaft that's ready to handle the increased demands of the 

racer, as well as a counterbalancer to reduce vibration. The 

crankcase also houses the oil tank, which helps to centralize 

mass for unmatched handling while making maintenance easier.
    Tuned Camshafts: Camshafts have been revised to help 

maximize the engine's impressive power output from off the 

line all the way up to the top end.

Chassis/Suspension

    Race-Ready Ergonomics: The body configuration allows more 

room for the racer to move around during the moto. The seat is 

narrow in the front, yet wide and padded in the rear to reduce 

fatigue.
    Durable Rigid Wheels: The wheels have been designed with 

the inner lip rolled in. This increases the rigidity, allowing 

a reduction in weight while maintaining strength.
    Wide Track and Maxxis? Tires: Wheels are set motocross-

spec wide, near the maximum allowable 50 inches, for great 

cornering speed. Maxxis? tires help provide excellent handling 

and control. At 20 inches in the rear and 21 inches in the 

front, they provide better ground clearance than the 

competition.
    Adjustable Handlebar: Large diameter, tapered handlebar 

reduces vibration and are mounted on 4-way clamps for 

exceptional adjustability. The two sets of holes in the 

handlebar crown and the eccentric clamps allow a rider to 

choose the standard setting, 10mm or 20mm forward, or 10mm 

back.
    Wide Footpegs: Foot pegs are a generous 2.6 inches wide, 

something riders will appreciate every time they want to get 

up on the pegs.
    Advanced Frame: The frame is a combination of aluminum and 

steel for light weight. The frame member under the engine is 

steel, used for its combination of strength and low profile. 

This allows the engine to sit lower overall for excellent mass 

centralization for unmatched handling. The aluminum frame is 

bolted together, rather than welded, for maximum durability.
    Long A-Arm Suspension: The front frame is as narrow as 

possible at the A-arm mounting points. This increases the A-

arm length and reduces changes in camber as the suspension 

travels through its full range of motion.
    High-Performance Shocks: The front KYB? shocks are longer 

for increased stroke with superb bump absorption and excellent 

anti-bottoming characteristics, and they have Kashima? coating 

for smooth operation. 9.8 inches of wheel travel means this 

racer is up to even the most challenging tracks.
    Swingarm Rear Suspension: The rear swingarm is crafted of 

strong, gravity-fed aluminum, and is matched to a fully 

adjustable 46mm KYB? piggyback shock for excellent handling. 

Rear wheel travel is 11.0 inches for comfort even on tough 

terrain.

Additional Features

    Light Throttle Action: The throttle lever requires low 

effort - less fatigue during long motos.
    Compact LED Indicators: The discrete panel on the fender 

in front of the rider gives vital indicators about low fuel, 

coolant temperature, check engine, and neutral gear via an LED 

display.

Engine

    Engine Type: 449cc liquid-cooled DOHC 4-stroke; 5 titanium 

valves
    Bore x Stroke: 95.0mm x 63.4mm
    Compression Ratio: 11.8:1
    Fuel Delivery: Yamaha Fuel injection (YFI), 42mm
    Ignition: TCI: Transistor Controlled Ignition
    Starting System: Electric
    Transmission: 5-speed; assist and slipper clutch
    Final Drive: O-ring chain; 2WD

Chassis

    Suspension / Front: Independent double wishbone w/Kashima 

coated piggyback shocks; high/low speed compression, rebound 

and threaded preload adjustment, 9.8-in travel
    Suspension / Rear: Cast aluminum swingarm w/piggyback 

shocks; high/low speed compression, rebound and threaded 

preload adjustment, 11.0-in travel
    Brakes / Front: Dual hydraulic disc
    Brakes / Rear: Wave-style hydraulic disc
    Tires / Front: AT21 x 7-10 Maxxis?
    Tires / Rear: AT20 x 10-9 Maxxis?

Dimensions

    L x W x H: 70.7 in. x 48.8 in. x 41.9 in.
    Seat Height: 31.9 in.
    Wheelbase: 50.0 in.
    Ground Clearance: 9.3 in.
    Fuel Capacity: 2.6 gal.
    Wet Weight: 405 lb.
    Lighting: Dual 30W Krypton headlights and LED brake light