2011 Kawasaki KX450F | Features Video

MX Video

The new 2011 Kawasaki KX450F has a race-ready engine is compact and light, with a short 100mm cylinder head and a 12.5:1 compression ratio. A wedge-shaped crank offsets 60 percent of the crankshaft’s reciprocating weight, producing an effective "counterweight" effect.

This is on par with Kawasaki’s factory racers and helps reduce engine vibration, smooths power delivery and enhance low-rpm throttle response. A stainless steel exhaust pipe connects to the revised silencer, which uses long-fiber packing material to maximize service intervals.

A rubber-damping collar in the rear silencer mount provides a boost to long-term durability. The KX450F’s Digital Fuel Injection (DFI) automatically adjusts to suit track and climate conditions, and offers stable fuel metering even when landing from jumps in tough motocross conditions.

The DFI system includes a compact and lightweight ECU, a 43mm throttle body, a lightweight aluminum fuel pump and an ultra-fine atomizing injector. Set at a 45-degree angle for ideal mid-range power, the 10-hole injector sprays precise, 60-micron fuel particles for smooth power delivery and accurate engine response throughout the rpm range.

Designed specifically for motocross, the KX450F’s lightweight DFI system doesn’t require a battery; the engine can be started within three rotations of the crankshaft using only the electricity generated through the initial stroke of the kickstarter.

An optional ECU Setting Tool allows racers to select from several different ECU data maps, or fine-tune a custom map that alters fuel injection and ignition timing to suit different tracks and conditions. The tool can also be used as a data logger, recording up to six hours of data, including engine rpm, degree of throttle opening, engine boost, coolant and air temperatures, ignition timing, fuel adjustments, gear position and system voltage.

At a glance…

• Powerful engine

• Revised

suspension settings

• Improved

shifting performance

• Revised


• Refined ECU


• Easier fuel

injection calibration system access

• Still easy

to start

Engine Overview

• 449cc liquid-cooled, DOHC, four-stroke single

• Bridged-box

bottom piston design offers optimal engine performance

• Reinforced

crankcase is strong and durable

• 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


High-acceleration cams help the engine rev quickly

Maintenance-free automatic cam chain adjuster

• Large

airbox flap helps prevent mud and water from entering

Bridged-box Bottom Piston

• Same design as used on our factory racers; offers improved

performance at all rpm

• Lighter and

more durable than traditional piston designs

• Short

piston skirt features low-friction coating for reduced mechanical losses

• Reinforced

external ribs for strength and durability

• Revised

profile with fully flush internal bracing results in a lighter, stronger


• Short

piston pin offers increased strength

Cylinder Head

• Compact head is only 100mm tall

• 36mm

titanium intake and 31mm 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

• Camshafts,

lobes and tappet surfaces feature a soft-nitride treatment for long wear

and high-rpm reliability


• Crankshaft with high inertial mass helps maximize rear wheel


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

and connecting rod feature a special carburizing and quenching treatment

to maximize rigidity

Digital Fuel Injection

• Self-adjusts to atmospheric changes for easier starting,

sharper throttle response and optimized power and stability when


• It is not

necessary to re-tune, or change any jets to suit climatic conditions

like on a carbureted model

• 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

• 43mm

throttle body uses a progressive throttle linkage to deliver airflow in

much the same way as an FCR carburetor

• Using two

linked shafts, the throttle body opens more quickly after reaching the

3/8 open position

• Lightweight

throttle body is approximately half the weight of a FCR carburetor,

saving over one pound in weight

• Fast-idle

knob on the throttle body allows riders to increase engine speed when

starting a cold engine

• Fuel

injector set at 45 degrees, the optimum angle for mid-range power

High-performance ECU

• 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


• The system

delivers electricity to FI system in sequence: first the ECU, then the

fuel pump, and finally the injector for quick, easy starting

• Starting

can be accomplished in a single kick

• 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

Optional User ECU Setting Tool

• Allows racers to reprogram the ECU’s data maps for volume of

fuel injected and ignition timing to alter engine characteristics to

suit rider preferences

• The tool

can also be used as a data logger, recording up to six hours of data,

including engine rpm, degree of throttle opening, engine boost, coolant

temp, air temp, ignition timing, fuel adjustments, gear position and

system voltage

Lightweight Aluminum Fuel Pump

• Located in the fuel tank but at a new angle to help prevent

damage in extremely rough riding conditions

• 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


• 1.9-gallon

fuel tank is formed using a rotational molding process

Easy Starting

• 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

• Compression

release features 1.0mm of valve lift, to minimize the required kicking


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

• Shrouds

feature a slim design that melds with the radiators’ design

• Radiator

louvers feature four small blades set at a shallow angle for minimum

overlap and maximum air flow

Strong and Durable Clutch

• Clutch assembly provides a direct feel and superb control

• Excellent

oil drainage contributes to more direct feel

• Friction

plates with substantial friction material contribute to a more direct


• Large

operating plate pusher reduces the clearance between the pusher and the

input shaft hole, improving clutch operation

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

• Thinner

inner-link chain is light and strong

Sprocket-style chain drive roller reduces the effect of driveline lash,

helping smooth engine braking and facilitating additional corner entry



• Short, one-piece stainless steel exhaust pipe contributes to

optimum mid-high rpm performance

• Optimized

exhaust routing contributes to improved ergonomics

• High-volume

silencer helps meet noise regulations

• currently 94dB

• Right side

panel has special passageway to help cool the silencer

Powerful Disc Brakes

• Rear brake pad material offers strong braking performance

• Powerful

twin-piston hydraulic front caliper

• Lightweight

semi-floating 250mm petal-type front brake rotor

• Single

piston hydraulic rear caliper squeezes lightweight 240mm petal-type


Light, Slim Chassis

• Revised engine mount brackets optimize frame rigidity for

better handling

• Lightweight

steering stem shaft contributes to light, nimble handling

• Main frame

spars are 68mm tall and 24mm 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

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

• Alloy

swingarm features a cast front section, tapered hydroformed spars and

forged chain adjusters

• Uni-Trak®

rear suspension linkage ratio maximizes rear traction performance

• Suspension

arm is mounted below the swingarm to allow a longer rear suspension

stroke and more precise tuning

Front Fork

• Race-oriented suspension settings offer maximum overall


• Revised

damping settings 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

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

• Wrap-around

fork tube guards offer effective protection for the sliders

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


• Kayaba rear

shock features a large 50mm piston

• Rear shock

features dual compression adjustability, allowing high-speed and

low-speed damping to be tuned separately

• Also

features Kashima Coat treatment on the cylinder for reduced friction and

smoother suspension action

• Easy

adjuster access for track-side suspension tuning

Rider Interface and Styling

• Dual injected two-tone, one-piece plastic shrouds and side

number plates

• Optimized

exhaust routing contributes to improved ergonomics

• Right side

panel has special passageway to help cool the silencer

• Black

plastic covers, triple clamps, engine covers, and black alumite-coated

rims – just like Kawasaki’s factory teams

• Wide 50mm

footpegs provide excellent feel and a comfortable platform

• Frame is

wider at the ankles to offer optimum grip, narrows below the seat to

allow a slim riding position

• 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

Additional Features

• 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 on the fly

• Increased

front axle collar diameter transmits more feedback from the contact

patch to the rider

• Ribless

rear hub and butted spokes offer light weight and excellent durability

• Rear

caliper guard helps protect the caliper from damage