SubscribeYZ450F
The Yamaha dirt bike that started the four-stroke revolution is back with some changes for next year, mostly from chassis refinements. Subtle modifications to the suspension improve handling, and head and exhaust design delivers stronger low-to midrange power without sacrificing top end power.
NEW FOR 2009 Top triple clamp has two sets of mounting holes, providing four handlebar positions to suit a wide variety of riders: standard, 10mm back, or 10mm, or 20mm forward.
Features include a ProTaper aluminum handlebar in adjustable clamps, titanium shock spring, gripper seat and Excel rims. A 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 durability.
New seat cover has great grip and more durability, and it’s easy to clean. Premium drive chain has gold colored plates for outstanding looks.
Newly designed swingarm is lighter and helps rigidity balance for improved 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 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.
ENGINE 449cc, five-valve, DOHC, liquid-cooled engine is 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. Primary kickstarting with automatic decompression and convenient, handlebar-mounted hot start lever. Large-capacity radiator is reinforced for greater strength.
CHASSIS Extensively tested aluminum frame uses a mix of alloy castings, forgings and extrusions to produce a tuned-flex frame. Speed-Sensitive System 48mm KYB fork damping force is controlled by piston speed and provides a smoother, more precise ride. Titanium-sprung, four-way adjustable rear shock with Kashima-coated internals reduces friction. 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.
