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Introduction
Did Somebody Say Motor?
In the 450cc motocross game, the only thing that matters to serious
racers is top-tier performance and running up front. And for
2011, the best tool for the job is once again a lime green one
Kawasaki's reworked and revised KX™450F. In this arena
you can't stand still technically, which is why Kawasaki engineers
scrutinized every system and component of the race-winning 2010
model and came up with a host of tweaks that'll have red, blue,
orange and yellow wondering what hit 'em.
The latest open-class KX starts with the primary pieces that
allowed the 2010 KX to win more Supercross events than any other
bike last year a brutally fast 449cc DOHC four-stroke single
packing a broad spread of power housed in a lightweight-yet-strong
aluminum frame connected to a suspension designed to offer compliance,
high-speed stability and whoop-sucking performance all moto long.
It was an ideal platform on which to win the majority of races
in 2010, and that trend promises to continue with the revised,
even faster 2011 model.
Last year, the KX450F featured a number of engine refinements,
including the first ever production use of a bridged-box bottom
piston (more high-end power and better over-rev characteristics),
revised cam timing for better mid- and top-end performance and
a reinforced cylinder sleeve and crankcase for improved durability.
This year there's even more. The bridged-box bottom piston shape,
for instance, has been modified to meld with the upgraded, higher-volume
muffler, which is quieter than last year's unit. The ECU has
been tweaked to provide a hotter and longer-duration spark for
improved low-rpm response. The shift mechanism incorporates a
larger internal roller and stronger shift-spring tension for
more positive shifting. Finally, the fuel-injection system's
Calibration Kit software has been updated, while the controller
harness and connector have been modified for easier use.
Changes in the chassis department are equally impressive, and
show the results of our race team's effect on development. First
up are revisions to the engine mount brackets that optimize chassis
flex and improve handling. Next, the engineers revised the damping
settings for the massive fork tubes for even better performance.
For that factory-bike touch there are also blue-anodized compression
damping adjuster caps in place of last year's silver ones. Damping
settings on the rear shock have also been revised, and it, too,
gets a blue-anodized compression adjuster. The seat features
a new side-surface texturing for increased rider grip while aboard,
and the drive chain guide has been thoroughly beefed up for increased
durability; testing shows it to be nearly three times more durable
than the unit fitted to the 2010 machine.
The race-ready engine is compact and light, with a short 100mm
cylinder head and a 12.5:1 compression ratio. A wedge-shaped
crank web 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 enhances 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.
The engine's phenomenal power is delivered through a clutch that
features an ultra-light operating plate with superb oil drainage
and beefy friction plates. The entire assembly is designed to
provide exceptional clutch feel and durability. The drive chain
features thin inner links and a slight weight savings relative
to typical designs to help boost acceleration. The revised suspension
damping settings provide lighter handling, improved suspension
action, increased comfort and greater cushioning when landing
from jumps.
The 2011 KX450F's D-shaped aluminum swingarm features a cross
section with narrow ribs and thin walls. It pivots high in the
aluminum frame to maximize rear wheel traction. Mounting the
arm of the Uni-Trak® rear suspension linkage below the swingarm
provides a long rear suspension stroke and facilitates precise
shock tuning.
Complementing the responsive chassis is a Kayaba Air-Oil-Separate
(AOS) fork that offers precise cornering and sharp handling.
The fork features a Diamond-Like Carbon (DLC) coating on the
outer surface of the inner fork tubes to minimize stiction when
the fork is exposed to lateral forces that would otherwise restrict
slide action. The result is smooth and precise response, especially
during cornering. Overall suspension action is extremely smooth
due to a friction-reducing Kashima Coat treatment on the inside
surfaces of the outer fork tubes and the rear shock reservoir.
Wrap-around fork guards provide excellent protection for the
sliders.
The 2011 KX450F's Kayaba rear shock's revised damping settings
contribute to improved wheel control and impact performance when
landing from jumps. It features a large 50mm piston and a Kashima
Coat treatment on the shock internals to help maintain a plush
feel throughout the toughest motos. Easily accessible dual compression
adjusters allow high- and low-speed damping to be tuned separately,
giving mechanics and riders the ability to easily fine tune the
suspension for difficult track conditions.
A slim seat design with firm urethane foam and a non-slip top
and side surface provides even more seated and standing grip
while retaining excellent rider mobility. The frame echoes the
slim profile at the top, but widens at the lower end by the ankles
to provide the rider with better feel and control. Completing
the rider interface are wide 50mm footpegs that offer tenacious
grip and a comfortable platform.
The 2011 KX450F is available in Kawasaki Lime Green, with black
alumite-coated rims and aggressive graphics for a factory appearance.
Racers who ride their KX450F at designated events are eligible
to receive support from Team Green™, Kawasaki's amateur
racing support program. Each year, Team Green provides regional
support vehicles and highly trained technicians at more than
100 events throughout the United States, offering technical information
and assistance to those who race Kawasaki products. Kawasaki
also offers a comprehensive contingency program for amateur and
professional riders who place well at designated events.
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Features
At a glance
· Massively powerful engine
· Revised suspension settings
· Improved shifting performance
· Revised seat
· Refined ECU settings
· 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 threshold
· 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 piston
· 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
· Crankshaft with high inertial mass helps maximize rear
wheel traction
· 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
jumping/landing
· 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 starter
· 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 riding
· 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 power
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 feel
· 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 control
Exhaust
· 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 rotor
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
performance
· 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 testing
· 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
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Technical Specifications
Engine: Liquid-cooled, four-stroke
single with DOHC and four-valve cylinder head
Displacement: 449cc
Bore x stroke: 96.0 x 62.1mm
Compression ratio: 12.5: 1
Fuel System: 43mm Keihin throttle body
Ignition: Digital DC-CDI
Transmission: Five-speed
Rake / trail: 26.7 degrees / 4.6 in.
Front suspension / wheel travel: Uni-Trak® linkage system
and Kayaba shock with 50mm piston, 22-position low-speed and
stepless high-speed compression damping, 33-position rebound
dampening and fully adjustable spring preload / 12.4 in.
Rear suspension / wheel travel: Uni-Trak® linkage system
and Kayaba shock with 50mm piston, 22-position low-speed and
stepless high-speed compression dampening, 33-position rebound
dampening and fully adjustable spring preload / 12.4 in.
Front tire size: 90/100-21
Rear tire size: 120/80-19
Front brakes: Single semi-floating 250mm petal disc with dual
piston caliper
Rear brakes: Single 240mm petal disc with single-piston caliper
Overall length: 86.0 in.
Overall width: 32.3 in.
Overall height: 50.4 in.
Wheelbase: 58.3 in.
Ground clearance: 13.2 in
Seat height: 37.8 in.
Curb weight: 249.9 lbs.
Fuel capacity: 1.9 gal.
Color Choices: Lime Green
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