2010 Kawasaki KX™450F

Additional Features

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

Aluminum Swingarm

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

At a Glance . . .

• Revised Suspension Settings
• Refined Fuel Injection
• More Powerful Engine
• Still Super-Easy to Start!

Better Cooling

• High-capacity Denso radiators feature tightly packed cores and a fin design that delivers superior cooling efficiency
• New radiators are 10 mm taller and 7.6 mm wider, with increased fin and tube pitch to provide a extra strength and better resistance to mud build-up
• Because the new radiators are stronger, reinforcing brackets could be eliminated, resulting in lower overall weight
• New shrouds feature a slightly slimmer design that is fine-tuned to accommodate the new radiators
• Radiator louvers feature four small blades set at a shallow angle, for minimum overlap and maximum air flow

Close-ratio 5-speed Transmission

• 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
• New chain with thinner inner links offers 20 g weight savings
• 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
• New crankshaft with a slightly higher inertial mass helps boost rear wheel traction
• End result is reduced engine vibration, smoother power delivery and increased performance, with a noticeably snappier response at low rpm
• Wedge-shaped crank web provides enough offsetting moment for a 60 percent balance factor – this is similar to the crank balance in Kawasaki’s factory race engines

Cylinder Head

• Camshafts, lobes and tappet surfaces feature a soft-nitride treatment for long wear and high-rpm reliability
• New intake camshaft features a revised sprocket / shaft arrangement which advances intake valve timing by two degrees, to suit revised engine characteristics 
• Compact head is only 100 mm tall
• Double valve springs allow a short cylinder head height and help ensure stable valve operation
• 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

Digital Fuel Injection

• Ultra-fine atomizing injector with 12 holes sprays particles with a droplet size of 60 µ for smooth power deliver and smooth engine response throughout the throttle range
• 43 mm throttle body uses a progressive throttle linkage to deliver airflow in much the same way as an FCR carburetor.
• Lightweight throttle body is approximately half the weight of a FCR carburetor, saving over one pound in weight
• Using two linked shafts, the throttle body opens more quickly after reaching the 3/8 open position
• Fuel injector set at 45°, the optimum angle for mid-range power
• Fast-idle knob on the throttle body allows riders to increase engine speed when starting a cold engine
• Self adjusts to atmospheric changes for easier starting, sharper throttle response and optimized power, and power stability when jumping / landing

Easy Starting

• 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
• Compression release features 1.0 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

Engine Overview

• A forward lean angle of 3° puts the engine in the ideal position for maximum traction
• Right-side crankcase reinforced at lower engine mount for increased strength and durability
• Maintenance free screw-type automatic cam chain adjuster
• Tuned for a broad powerband with the torque curve set just under the wheel spin threshold
• High-acceleration cams help the engine rev quickly
• Large flap inside the airbox helps prevent the ingress of mud and water
• 449 cc liquid-cooled, DOHC, four-stroke single cylinder skirt strengthened to handle increased engine performance

Exhaust

• High volume silencer body helps meet noise regulations currently 99 dB
• Optimized exhaust routing contributes to improved ergonomics
• One-piece stainless steel exhaust pipe is 40 mm shorter than the ’09 unit, contributing to improved mid-high rpm performance
• Right side panel has special passageway to help cool the silencer

Front Fork

• Friction-reducing Kashima Coat on the inside of the fork outer tubes contributes to smooth suspension action (especially at the initial part of the stroke) and a superb ride feel
• Revised spring rate and damping settings work with the less rigid steering stem to offer improved action and increased comfort during the initial phase of the suspension stroke
• 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
• Wrap around black fork tube guards offer effective protection for the inner fork tubes
• Race-oriented suspension settings offer maximum over-all performance
• 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

High Performance ECU

• 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
• New ECU programming and revised settings offer improved response at low-mid rpm
• 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
• Starting can be accomplished in a single kick

Improved Clutch

• Material trimmed from the spring holders and outer surface of the plate, to optimize rigidity and improve oil drainage, contributing to more direct feel
• New clutch provides a more direct feel and increased control
• Friction plates feature approximately 75% more friction material, contributing to a more direct feel
• Operating plate pusher features an increased outer diameter, to reduce the clearance between the pusher and the input shaft hole, improving clutch operation

Light, Slim Chassis

• New steering stem shaft with lower rigidity contributes to lighter 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 down tube that is now 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

• Fuel return hose from the pressure regulator helps ensure there is always fuel in the inlet port, preventing stalls due to fuel splashing and enabling riders to use all the fuel
• 1.8 gallon fuel tank is formed using a rotational molding process
• 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
• Located in the fuel tank

New Bridge-box Bottom Piston

• Shorter piston pin has a smaller inner diameter for increased strength
• Reinforced external ribs for strength and durability
• First mass-production use of a bridged-box bottom piston design
• 6 mm shorter piston skirt features a low-friction coating for reduced mechanical losses
• Revised profile with fully flush internal bracing, results in a lighter, stronger piston
• 7 grams lighter than the ’09 piston
• Same design as used on our factory racers, offers improved performance at all rpm

Powerful Disc Brakes

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

Rear Shock

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

Rider Interface and Styling

• Optimized exhaust routing contributes to improved ergonomics
• Dual injected 2-tone, 1-piece plastic shrouds and side number plates
• Wide 50 mm foot pegs 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
• Slim seat design uses firmer urethane foam which keeps its original shape longer for the best possible ergonomics and feel
• 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
• Seat has a slip-resistant top surface for good grip when seated and smooth sides for excellent rider mobility