The bike that started the four-stroke revolution benefits from significant chassis and engine refinements, providing the power delivery, handling and the edge that can keep you on the podium.
For 2007, the bike that started the four-stroke revolution benefits from significant chassis and engine refinements that ensure the five-titanium-valved YZ450F remains at the head of the open-class pack. Modifications to the light and strong aluminum frame and suspension mean light, precise, confident handling at any speed. Five-speed gearbox provides maximum flexibility and the right gear for a wide range of riding environments. Ready to race straight out of the crate - with a ProTaper aluminum handlebar in adjustable clamps, titanium shock spring, ti footpegs, gripper seat, etc.
New for 2007
Replacing the upper cast triple clamp with a light and strong forging, slightly reducing steering head rigidity, and the use of lighter outer fork tubes; lighter wheel rims and light wave-type brake rotors add up to super-accurate, super-responsive steering. Increasing the length of the rear shock by 1.5mm provides sharp handling. Replacing steel damping adjusters with aluminum ones removes even more weight from the four-way adjustable, titanium-sprung rear suspension unit. A more rigid clutch pressure plate helps put power to the ground and dissipates heat more efficiently, especially during partial-clutch operation. Shorter lever stroke with 12-percent reduced effort means instant response. New, titanium exhaust pipe fattens low- and mid-range power while simultaneously adhering to 2007 AMA noise regulations. This year’s ProTaper aluminum handlebar bend raises the grips 8mm for an expanded cockpit. Forged bar clamps reduce weight for superior handling.
2007 Yamaha YZ450F
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. Revised CDI ignition keeps that amazingly broad and deep powerband hard-hitting, yet controllable. Lightweight, titanium valves and load-reduced springs minimize reciprocating mass for fast-revving, hard-hitting power delivery across the rev range. Additional weight-saving engine features include: small-design cam chain tensioner and oil pump, aluminum oil hose, all-titanium exhaust header, flange, bracket and heat shield and light CDI ignition unit. Primary kickstarting with automatic decompression and convenient handlebar-mounted hot start lever ensures easy restarts. Kick pinion gear is separate from the primary driven gear for smoother clutch engagement. Large-capacity radiator is reinforced for greater strength.
Aluminum frame uses a mix of alloy casting, forgings and extrusions to produce a tuned-flex frame that makes the YZ the finest handling motocross bike ever. Speed-Sensitive System 48mm Kayaba fork places transfer control valves (TCV) above the fork springs, so that damping force is controlled by piston speed; Eliminating mid-stroke damping force changes provides a smooth, precise ride. Titanium-sprung four-way adjustable rear shock with Kashina-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 - lighter fasteners for 2007 enhance weight distribution and handling. Lightweight front wheel hub for reduced unsprung weight and increased durability. Premium Dunlop knobbies provide unbeatable, competition-spec traction and great wear. Lightweight 21-inch front and 19-inch rear Excel rims are exceptionally durable and reduce unsprung weight.
“Gripper” style seat cover gives excellent feel and control, and the seat is lighter for 2007. Wide, cleated, folding titanium footpegs are light, strong, and provide excellent comfort, grip and ground clearance. Works-style clutch lever features oversize barrel adjuster for easy, on-the-fly adjustability of lever/cable play. Cleated rear brake lever and folding shift lever tip offer superb grip and excellent durability. Repackable exhaust silencer. Durable, comfortable handlebar grips. Stainless steel clutch cable for longer life.