2011 Kawasaki KX™450F

Additional Features

• Clutch cable boot features a large quick adjuster, making it easy for riders to adjust play in the clutch cable on the fly
• Ribless rear hub and butted spokes offer light weight and excellent durability
• Skid plate made of resin material offers great protection without excess weight
• Increased front axle collar diameter transmits more feedback from the contact patch to the rider
• Rear caliper guard helps protect the caliper from damage

Aluminum Swingarm

• Cross-section design contributes to light handling
• Tapered "D" shape swingarm provides ideal rigidity for excellent stability, and is lighter than a comparable box-section unit
• Uni-Trak® rear suspension linkage ratio maximizes rear traction performance
• Alloy swingarm features a cast front section, tapered hydroformed spars and forged chain adjusters
• Suspension arm is mounted below the swingarm to allow a longer rear suspension stroke and more precise tuning

Bridged-box Bottom Piston

• Short piston pin offers increased strength
• Revised profile with fully flush internal bracing results in a lighter, stronger piston
• Same design as used on our factory racers; offers improved performance at all rpm
• Short piston skirt features low-friction coating for reduced mechanical losses
• Lighter and more durable than traditional piston designs
• Reinforced external ribs for strength and durability

Close-ratio 5-speed Transmission

• Thinner inner-link chain is light and strong
• 5-speed transmission and low-rpm engine response combination offers riders more gear options for traversing rough sections or getting into the rhythm of a course easily so they can focus more on racing
• Sprocket-style chain drive roller reduces the effect of driveline lash, helping smooth engine braking and facilitating additional corner entry control

Crankshaft

• Crankshaft and connecting rod feature a special carburizing and quenching treatment to maximize rigidity
• Wedge-shaped crank web provides enough offsetting moment for a 60 percent balance factor – and is similar to the crank balance in Kawasaki’s factory race engines, resulting in reduced engine vibration, smoother power delivery and increased performance, with a noticeably snappier response at low rpm
• Crankshaft with high inertial mass helps maximize rear wheel traction

Cylinder Head

• 36 mm titanium intake and 31 mm exhaust valves with aluminum spring retainers minimize reciprocating weight and cylinder height to help ensure reliable valve control at high rpm
• Double valve springs allow a short cylinder head height and help ensure stable valve operation
• Compact head is only 100 mm tall
• Camshafts, lobes and tappet surfaces feature a soft-nitride treatment for long wear and high-rpm reliability

Digital Fuel Injection

• Lightweight throttle body is approximately half the weight of a FCR carburetor, saving over one pound in weight
• It is not necessary to re-tune, or change any jets to suit climatic conditions like on a carbureted model
• Fuel injector set at 45 degrees, the optimum angle for mid-range power
• 43 mm throttle body uses a progressive throttle linkage to deliver airflow in much the same way as an FCR carburetor
• Ultra-fine atomizing injector with 10 holes sprays particles with a droplet size of 60 microns for smooth power delivery and engine response throughout the throttle range
• Fast-idle knob on the throttle body allows riders to increase engine speed when starting a cold engine
• Using two linked shafts, the throttle body opens more quickly after reaching the 3/8 open position
• Self-adjusts to atmospheric changes for easier starting, sharper throttle response and optimized power and stability when jumping / landing

Easy Starting

• Compression release features 1 mm of valve lift, to minimize the required kicking power
• Strong output from the large ACG rotor provides enough electrical power for the battery-less FI system to enable true one-kick starting without using a battery
• Equipped with an automatic compression release (ACR) system for quick and easy starting. The dual-weight centrifugal decompression system is fitted to the exhaust cam.

Efficient Cooling

• High-capacity Denso radiators feature tightly packed cores and a fin design that delivers superior cooling efficiency
• Radiators don’t need reinforcing brackets, which results in lower overall weight
• Radiator louvers feature four small blades set at a shallow angle for minimum overlap and maximum air flow
• Shrouds feature a slim design that melds with the radiators’ design

Engine Overview

• High-acceleration cams help the engine rev quickly
• Maintenance-free automatic cam chain adjuster
• 449 cc, liquid-cooled, DOHC, four-stroke single
• Bridged-box bottom piston design offers optimal engine performance
• Large airbox flap helps prevent mud and water from entering
• A forward lean angle of 3 degrees puts the engine in the ideal position for maximum traction
• Tuned for a broad powerband with the torque curve set just under the wheelspin threshold
• Reinforced crankcase is strong and durable

Exhaust

• Optimized exhaust routing contributes to improved ergonomics
• High-volume silencer helps meet noise regulations currently 94 dB
• Short, one-piece stainless steel exhaust pipe contributes to optimum mid-high rpm performance
• Right side panel has special passageway to help cool the silencer

Front Fork

• Diamond-like Carbon (DLC) coating on the outer surface of the inner fork tubes offers minimum stiction when the fork is exposed to lateral forces that would usually hamper slide action. The result is improved fork response, especially during cornering.
• Friction-reducing Kashima coat on the inside of the fork’s outer tubes contributes to smooth suspension action (especially at the initial part of the stroke) and a superb ride feel
• Race-oriented suspension settings offer maximum overall performance
• Revised damping settings offer improved action and increased comfort during the initial phase of the suspension stroke
• Wrap-around fork tube guards offer effective protection for the sliders
• Kayaba Air-Oil-Separate (AOS) fork keeps oil and air in separate chambers for stable damping performance during long motos. Low-friction fork seals contribute to smooth action.

High Performance ECU

• The system delivers electricity to FI system in sequence: first the ECU, then the fuel pump, and finally the injector for quick, easy starting
• The compact, lightweight ECU, located on the front of the steering head behind the number plate, was designed specifically for motocross use. The fuel pump relay is integrated with the ECU to help cope with the shocks and vibrations of motocross riding.
• New ECU programming and revised settings offer improved response at low-to-mid rpm
• No battery needed; the engine can be started with only three rotations of the crankshaft using the electricity generated by a single kick of the starter
• Starting can be accomplished in a single kick

Light, Slim Chassis

• Lightweight steering stem shaft contributes to light, nimble handling
• Revised engine mount brackets optimize frame rigidity for better handling
• Main frame spars are 68 mm tall and 24 mm wide to provide an ideal balance between stiffness and compliance
• Weight-saving features include a slim head pipe, narrow cross-section and a downtube formed with a swaging (squeezing and hammering) process
• Swingarm pivot is located high in the frame to maximize rear wheel traction

Lightweight Aluminum Fuel Pump

• Features a rubber fuel filter cover that wraps around the inlet port and acts as a fuel trap to help ensure a stable fuel supply during vigorous motocross riding
• 1.9-gallon fuel tank is formed using a rotational molding process
• Located in the fuel tank but at a new angle to help prevent damage in extremely rough riding conditions

Powerful Disc Brakes

• Rear brake pad material offers strong braking performance
• Single piston hydraulic rear caliper squeezes lightweight 240 mm petal-type rotor
• Lightweight semi-floating 250 mm petal-type front brake rotor
• Powerful twin-piston hydraulic front caliper

Rear Shock

• New damping settings contribute to increased stability and improved impact performance when landing from jumps
• Rear suspension settings and linkage ratios derived from extensive rider testing
• Also features Kashima coat treatment on the cylinder for reduced friction and smoother suspension action
• Rear shock features dual compression adjustability, allowing high-speed and low-speed damping to be tuned separately
• Easy adjuster access for track-side suspension tuning
• Kayaba rear shock features a large 50 mm piston

Rider Interface and Styling

• Wide 50 mm footpegs provide excellent feel and a comfortable platform
• Black plastic covers, triple clamps, engine covers, and Black alumite-coated rims – just like Kawasaki’s factory teams
• Optimized exhaust routing contributes to improved ergonomics
• Dual injected two-tone, one-piece plastic shrouds and side number plates
• Frame is wider at the ankles to offer optimum grip, narrows below the seat to allow a slim riding position
• Right side panel has special passageway to help cool the silencer
• Slim seat design uses firmer urethane foam that keeps its original shape longer for the best possible ergonomics and feel
• Seat has a slip-resistant top surface for good grip when seated and a new material along the sides for extra grip when standing

Strong and Durable Clutch

• Clutch assembly provides a direct feel and superb control
• Large operating plate pusher reduces the clearance between the pusher and the input shaft hole, improving clutch operation
• Friction plates with substantial friction material contribute to a more direct feel
• Excellent oil drainage contributes to more direct feel