Key Features:

• The bike that started the four-stroke revolution benefits from chassis refinements that ensure the five-titanium-valved YZ450F remains at the head of the open-class pack.
• Subtle modifications to the suspension mean light, precise, confident handling at any speed.
• Head and exhaust design delivers stronger low- to midrange power without sacrificing top end power.
• Ready to race straight out of the crate VbCrLfwith a ProTaper aluminum handlebar in adjustable clamps,
• titanium shock spring, gripper seat, Excel rims, etc.
• Five-speed gearbox provides maximum flexibility and the right gear for a wide range of riding environments.
• Dry sump lubrication system circulates more oil for the best durability in motocross.

New for 2009:

• Top triple clamp has two sets of mounting holes, providing 4 handlebar positions to suit a wide variety of riders: standard, 10mm back, or 10mm or 20mm forward.
• Newly designed swingarm is lighter and helps to achieve excellent rigidity balance for superb cornering and rear wheel traction.
• Lightweight suspension linkage is redesigned to match the new swingarm.
  New rear wheel hub is lighter and designed for the larger 25mm diameter axle (up from 22mm), helping to achieve the overall rigidity balance of rear suspension components.
• New axle blocks make chain adjustment a cinch.
• New clutch lever is shorter, stronger, and lighter, with a lever position adjuster to accommodate different riders. Quick adjuster makes maintenance easy.
• Front brake hose clamp is now aluminum, greatly reducing its weight.
• New seat cover has great grip and more durability, and it Is easy to clean.
• Premium drive chain has gold colored plates for outstanding looks.

Engine:

• 449cc, five-valve, DOHC, liquid-cooled engine is super-powerful yet tractable.
• 39mm Keihin FCR flat-slide carburetor with throttle position sensor (TPS) and leak jet delivers precise fuel/air mixture and instant throttle response.
• Lightweight titanium valves and load-reduced springs minimize reciprocating mass for fast-revving, hard-hitting power delivery across the rev range.
• Primary kickstarting with automatic decompression and convenient, handlebar-mounted hot start lever ensures easy restarts.
• Large-capacity radiator is reinforced for greater strength.

Chassis/Suspension:

• Extensively tested aluminum frame uses a mix of alloy castings, forgings and extrusions to produce a tuned-flex frame that makes the YZ the finest-handling motocross bike ever.
• Speed-Sensitive System 48mm KYB fork damping force is controlled by piston speed: provides a smoother, more precise ride.
• Titanium-sprung, four-way adjustable rear shock with Kashima-coated internals reduces friction for fantastic compliance and great handling.
• More weight savings come via two-piece (part aluminum, part plastic) engine protector plates and thin-walled engine guard construction.
• Removable aluminum rear subframe constructed of square-section tubing for light weight and easy maintenance.
• Lightweight front-wheel hub for reduced unsprung weight and increased durability.
• Lightweight front- and rear-brake calipers with aluminum pistons and anti-bubble front master cylinder; wave-style rotors reduce unsprung weight and deliver strong stopping power.

Additional Features:

• Wide (55mm) footpegs provide excellent boot traction and rider comfort.
• ProTaper aluminum handlebar for strength and performance.
• Works-style clutch lever features oversize barrel adjuster for easy, on-the-fly adjustability of lever/cable play.
• Repackable exhaust silencer.