Kawasaki released photos and specs for their 2006 motocross models today,
including the long-awaited KX450F four-stroke. The big news for 2006 is that
Kawasaki has dropped the KX125 from the lineup (at least in the U.S., according to
a Kawasaki press representative), presumably a result of poor sales in comparison to the KX250F four-stroke. Will two-stroke 125s disappear in 2006? We will have to wait to see what the other manufacturers do. Until then, here are the specs on the 2006 KX lineup. Keep in mind that the following text quotes Kawasaki’s press materials, and does not constitute MD editorial.

Kawasaki, the brand that introduced the motocross world to perimeter frames and aweinspiring
powerbands, has unveiled an all-new flagship in its leading-edge KX™ motorcycle line.
Every aspect of the 2006 KX450F, from its ultra-powerful four-stroke engine to the trick
aluminum frame and suspension, reflects its purpose as a championship-winning race bike.
Kawasaki engineers stressed every detail on the new, liquid-cooled, 449cc four-stroke
engine to ensure that its provides maximum power and traction. Featuring double overhead
cams, four valves and a Keihin FCR40 carburetor, it combines amazing acceleration with smooth
over-rev capability so the rider can use very ounce of its incredible power on the racetrack.
Hand-finished intake ports maximize intake efficiency, while lightweight titanium valves
and aluminum valve retainers reduce reciprocating weight for reliable valve control at high rpm.
Plus, double valve springs provide stable operation under intense racing conditions. To ensure
quick and easy starting, the KX450F features both an automatic compression release and hot
start system.

The KX450F utilizes newly designed, high-capacity Denso radiators, which provide
superior cooling under racing conditions. With its tightly packed radiator cores and new fin
design, the new radiators improve heat dispersion for consistent engine power characteristics and
dependability.

The KX450F comes equipped with a tapered titanium exhaust pipe that expands in
diameter from 38 to 41mm, contributing to its broad powerband, and the silencer features new,
long-fiber packing.

Kawasaki engineers have matched the high-tech engine to a new four-speed transmission.
Combined with a manual, multi-disc wet clutch, the four-speed transmission enables the rider to
take advantage of the engine’s inherently broad powerband on the racetrack; from accelerating
out of turns to high-speed straights, the rider can use the KX450F’s precise throttle control to
adjust speed nearly instantaneously. And to protect the underside of the engine and transmission,
the KX450F comes with a lightweight aluminum skid place.

The KX450F chassis has been designed to help the rider put the engine’s power to the
ground. To do this, Kawasaki engineers combined their experience designing steel perimeter KX
frames and techniques used to construct the Ninja® ZX™-10R sport bike chassis to create an allnew
aluminum perimeter frame. Comprised of forged, extruded and cast aluminum parts, the
strong twin-spar design gives the KX450F optimum balance of torsional and longitudinal
rigidity.

The frame was designed so that the center of gravity and key chassis dimensions would
work together to enhance the rear tire’s ability to drive the KX450F forward instead of squatting
under acceleration. Additionally, the four-stroke engine sits in an upright position within the new
frame to further aid overall traction.

Kawasaki then added complementary front and rear suspension to the KX450F. A
Kayaba AOS (Air-Oil-Separate) fork keeps oil and air in separate chambers for stable damping
performance during long motos. On the rear, the UNI-TRAK® rear suspension system features
an alloy swingarm with tapered spars and linkage ratios to maximize traction under acceleration.
Front and rear petal disc brakes provide stopping power for the KX450F. This design not
only helps to reduce unsprung weight, but the petal shape of the discs helps to clean the brake
pads for more efficient braking performance.

The slim profile of the KX450F frame, two-piece radiator shrouds that leave the upper
frame spars exposed, and careful design of the remaining bodywork make the KX450F feel light
and narrow beneath the rider.

The KX450F comes with a Renthal aluminum handlebar, while the seat uses a slipresistant
top surface for good grip when seated and smooth sides for enhanced rider mobility.
The KX450F also features titanium footpegs and footpeg brackets for reduced overall weight.
Complementing the KX450F’s ultra-high-performance design is aggressive bodywork
and graphics.

Kawasaki offers a number of optional parts for the KX450F, including a top mounting
clamp for an oversized handlebar, aluminum and steel rear sprockets, solid petal disc brake
rotors for wet racing conditions, optional springs for the front fork and rear shock, and a 20-inch
front wheel.

FEATURES

Engine
– 449cc liquid-cooled, four-stroke single
– Wide powerband extends into the over-rev

Top End
– High-acceleration cams help the engine rev more quickly
– Camshaft lobes and tappets feature soft-nitriding surface treatment for long wear and high-rpm reliability
– Hand-finished surfaces of the polished intake ports improve intake efficiency at all rpm
– Lightweight titanium 36mm intake and 31mm exhaust valves and aluminum valve retainers reduce
reciprocating weight for reliable valve control at high rpm
– Double valve springs help ensure stable valve operation
– Screw-type cam chain tensioner adjuster with pressure spring functions automatically
– Low-friction coating on piston skirt

Bottom End
– Crankshaft, rotor mass centralization, oil circulation, and ignition timing have been carefully examined to
help ensure ideal engine braking characteristics
– Crankshaft and connecting rod are sintered for additional rigidity

Starting
– Features highly reliable auto-decompression system; the dual-weight centrifugal decompression system
fitted to the exhaust cam eases starting, and its simple construction helps to ensure reliability
– Hot start system gives quick starts when the engine is hot, and the hot start lever is unitized with the clutch
lever
– The plunger actuating the hot starter has a U-packing seal to prevent water from getting into the carburetion
system

Exhaust
– Tapered all-titanium exhaust pipe expands in diameter from 38 to 41mm, contributing to both low- and
high-rpm performance
– Titanium exhaust pipe heat shield
– Silencer uses new, long-fiber packing

Cooling
– Newly designed, high-capacity Denso radiators deliver superior cooling efficiency
– Slim new radiators feature more tightly packed cores and a new fin design for enhanced heat dispersion

Shifting
– Four-speed transmission features new shift drum cam to minimize shift lever play

Frame
– All-aluminum perimeter frame is composite structure comprising forged, extruded and cast components
– The slim profile of the KX450F frame, two-piece radiator shrouds that leave the upper frame spars
exposed, and careful design of the remaining bodywork make the KX450F feel light and narrow beneath
the rider
– Titanium footpegs and footpeg brackets
– Aluminum skid plate

Front Suspension
– Kayaba AOS (Air-Oil-Separate) fork keeps oil and air in separate chambers for stable damping
performance during long motos
– Low-friction fork seals contribute to smooth action
– Plastic liners inside the fork sliders allow secondary tuning

Rear Suspension
® rear suspension system features linkage ratios to suit the new frame and swingarm – New UNI-TRAK
– Alloy swingarm uses cast front section, tapered hydroformed spars and forged chain pullers; the tapered
spars are shaped to match the balance of flex and rigidity required of the aluminum frame, and allow
additional clearance for the rear brake caliper when the rear suspension is fully compressed

Brakes
– Front and rear petal disc brakes help reduce unsprung weight
– Petal shapes of the discs help clean the brake pads for more efficient braking performance

Wheels
– 32-spoke rear wheel for reduced unsprung weight

From the Cockpit
– Renthal aluminum handlebars are standard
– Lightweight short-length grips feature a special pattern to reduce vibration transmitted from the bars to the
rider
– Seat uses a slip-resistant top surface for good grip when seated and smooth sides for excellent rider
mobility

Weight Savings
– Aluminum parts used instead of steel, including clutch cable elbow, clutch cable fitting nuts, fuel tank
fitting nuts, seat mounting brackets, front brake hose clamp and igniter stay bracket

Options
– Optional cable set-up allows manual operation of the decompressor via a lever on the right handle grip
– Top mounting clamp for an oversized handlebar
– Aluminum and steel rear sprockets with optional tooth sizes
– Solid petal brake rotors for wet racing conditions
– Optional springs for the front fork and rear shock
– 20-inch front wheel

SPECIFICATIONS*
Engine: Liquid-cooled, four-stroke single with DOHC and four valves
Displacement: 449cc
Bore x stroke: 96.0 x 62.1mm
Compression ratio: 12.0:1
Carburetion: Keihin FCR40
Ignition: Digital AC-CDI
Starting: Kick
Transmission: Four-speed with manual multi-disc wet clutch
Final drive: Chain
Frame: Aluminum perimeter
Rake / trail: 27 degrees / 4.6 in.
Front suspension / wheel travel: 48mm inverted AOS-type telescopic fork with 22-way compression
damping and 20-way rebound damping / 12.4 in.
Rear suspension / wheel travel: UNI-TRAK® linkage system with 22-way compression and rebound
damping, and fully adjustable spring preload / 12.4 in.
Front tire: 80/100-21 51M
Rear tire: 100/90-19 57M
Front brake: Single semi-floating 250mm petal disc with dual-piston caliper
Rear brake: Single 240mm petal disc with single-piston caliper
Overall length: TBA
Overall width: TBA
Overall height: TBA
Wheelbase: TBA
Ground clearance: TBA
Seat height: TBA
Dry weight: TBA
Fuel capacity: TBA
Color: Kawasaki Lime Green / Black
MSRP: TBA

Just two short years after it was introduced to American motocross racers, the
championship-winning KX™250F motorcycle has been revamped – even though it already has
five titles under its proverbial belt.

Numerous changes have been made to the potent KX250F. It produces significantly more
power than the 2005 model it replaces, and like the new flagship KX450F, the KX250F sports an
all-aluminum perimeter frame.

The 249cc, liquid-cooled, four-stroke engine now gives the KX250F a harder-hitting
powerband, especially from mid- to high-rpm, and it extends that smooth, traction-grabbing
power into the over-rev range.

Additional enhancements include revised intake and exhaust ports, and a revised
combustion chamber for stronger low- to mid-rpm performance, while new cam profiles and a
higher 13.5:1 compression ratio improve high-rpm performance. To compensate for the
increased output, the piston now has a thicker crown.

Other engine modifications include stiffer valve springs to help ensure reliable valve
control at high rpm; a surface-hardened crankshaft for additional rigidity; more efficient oil
pumps that increase oil flow by nearly 20 percent; a new stick ignition coil that reduces overall
weight; and newly designed, high-capacity Denso radiators that deliver superior cooling
performance due to their more tightly packed cores and new fin design. Kawasaki also revised
the timing and lift of the decompression system, so starting the KX250F is even easier.

The clutch and five-speed transmission have also been modified to include new friction
plate material and stiffer clutch springs for improved clutch feel, and the gears have beefier dogs
to match the more-powerful engine. Kawasaki engineers have also given the KX250F shift drum
a new cam to improve shifting feel.

The most visible change to the KX250F is the aluminum perimeter frame. As with the
KX450F, Kawasaki engineers combined their experience designing steel perimeter KX frames
and techniques used to construct the Ninja® ™ ZX -10R sport bike chassis to create an all-new
aluminum perimeter frame. Comprised of forged, extruded and cast aluminum parts, the strong
but light design gives the KX250F the best possible balance of torsional and longitudinal rigidity
necessary for superior handling characteristics.

The frame was designed so that the center of gravity and key chassis dimensions would
work together to enhance the rear tire’s ability to drive the KX250F forward instead of squatting
under acceleration. Additionally, the four-stroke engine sits in an upright position within the new
frame to further aid overall traction.

The slim profile of the KX250F frame, two-piece radiator shrouds that leave the upper
frame spars exposed, and careful design of the remaining bodywork make the KX250F feel light
and narrow beneath the rider.

The KX250F’s high-performance suspension has been designed to complement the new
frame. Up front, a Showa twin-chamber fork keeps the oil and air in separate chambers for
consistent damping performance during long motos. On the rear, a new UNI-TRAK® rear
suspension system, featuring an alloy swingarm with tapered spars and revised linkage ratios
maximizes traction under acceleration.

Front and rear petal disc brakes provide stopping power for the KX250F. This design not
only helps to reduce unsprung weight, but the petal shape of the discs helps to clean the brake
pads for more efficient braking performance.

In addition to aggressive new bodywork and a new seat, the KX250F comes with a
Renthal aluminum handlebar and an aluminum skid plate as standard.
To minimize overall weight, the KX250F utilizes aluminum instead of steel for several
components, including the clutch cable elbow, clutch cable fitting nuts, fuel tank fitting nuts, seat
mounting brackets, front brake hose clamp and igniter stay bracket. Kawasaki engineers also
eliminated the upper mounting brackets of previous designs for the plastic fork protectors.

Optional parts for the KX250F include magneto rotors with different inertias, a 12-tooth
countershaft sprocket, top mounting clamp for an oversized handlebar, aluminum and steel rear
sprockets, solid petal brake rotors for wet races, different springs for the front fork and rear
shock, manual decompression lever and cable, and a 20-inch front wheel.

FEATURES

Engine
– 249cc, liquid-cooled, four-stroke engine delivers hard-hitting power from mid- to high-rpm
– Wide powerband extends smoothly into the over-rev

Top End
– Revised intake and exhaust ports, and revised combustion chamber improve low- to mid-range
performance
– Rev-limiter settings and ignition timing have been revised to extend the engine’s over-rev capability
– New cam profiles help increase high-rpm performance without sacrificing low-end performance
– Piston features a thicker crown to compensate for increased power and higher compression ratio
– Once-piece magneto rotor offers improved reliability
– New stick ignition coil saves weight and offers improved performance

Bottom End
– Crankshaft is surface-hardened for additional rigidity
– Countershaft sprocket has more – and smaller – splines to increase reliability
– More efficient oil pumps increase oil flow by nearly 20 percent

Cooling
– Newly designed, high-capacity Denso radiators are slimmer
– Radiator features more tightly packed cores and a new fin design to deliver superior cooling efficiency

Shifting
– New friction plate material and stiffer clutch springs improve clutch feel
– New clutch lever design compensates for higher spring rate
– Five-speed transmission dogs are beefier to match the engine’s increased power
– Shift drum features new cam for improved shifting feel

Frame
– All-aluminum perimeter frame features composite structure, utilizing forged, extruded and cast components
– The slim profile of the frame, two-piece radiator shrouds that leave the upper frame spars exposed, and
careful design of the remaining bodywork make the KX™250F feel light and narrow beneath the rider

Front Suspension
– Showa twin-chamber fork keeps oil and air in separate chambers for stable damping performance during
long motos

Rear Suspension
® – New UNI-TRAK rear suspension system features revised linkage ratios to suit the new fame and
swingarm
– Alloy swingarm uses cast front section, tapered hydroformed spars and forged chain pullers; the tapered
spars are shaped to match the balance of flex and rigidity required of the aluminum frame, and allow
additional clearance for the rear brake caliper when the rear suspension is fully compressed
– Smaller rear chain guide reduces overall weight

Brakes
– Front and rear brakes utilize new petal discs, helping to reduce overall weight
– Petal discs help to clean the brake pads for more efficient braking performance

Wheels
– New rear wheel helps to reduce unsprung weight

From the Cockpit
– Renthal aluminum handlebar is strong and reduces overall weight
– Short-length grips feature a special pattern to reduce vibration transmitted from the bars to the rider

New Styling
– New bodywork and new seat have aggressive style

Options
– Different inertia magneto rotors
– 12-tooth countershaft sprocket
– Top handlebar clamp for an oversized bar
– Aluminum and steel rear sprockets with optional tooth sizes
– Solid petal brake rotors for wet racing conditions
– Optional springs for the front fork and rear shock
– Manual decompression lever and cable
– 20-inch front wheel

SPECIFICATIONS*
Engine: Four-stroke single with DOHC and four valves
Displacement: 249cc
Bore x stroke: 77.0 x 53.6mm
Cooling: Liquid
Carburetion: Keihin FCR37 and hot start circuit
Compression ratio: 13.5:1
Ignition: Digital AC-CDI
Transmission: Five-speed with wet multi-disc manual clutch
Final drive: Chain
Frame: Aluminum perimeter
Rake / trail: 27.5 degrees / 4.7 in.
Front suspension / wheel travel: 47mm inverted twin-chamber telescopic fork with 16-way
compression and rebound damping / 12.4 in.
Rear suspension / wheel travel: UNI-TRAK® linkage system with 13-way low-speed and 2-turn highspeed
compression damping, 17-way rebound damping and fully adjustable spring preload / 12.2 in.
Front tire: 80/100-21 51M
Rear tire: 100/90-19 57M
Front brake: Single semi-floating 250mm disc with dual piston caliper
Rear brake: Single 240mm disc with single-piston caliper
Overall length: TBA
Overall width: TBA
Overall height: TBA
Ground clearance: TBA
Seat height: TBA
Dry weight: TBA
Wheelbase: TBA
Fuel capacity: TBA
Color: Kawasaki Lime Green / Black
MSRP: TBA

Several motocross magazines hailed the 2005 Kawasaki KX™250 as one of the best allaround
two-stroke motocross bikes due to its sheer power, ideal handling and superb brakes. As
one magazine said, “The 2005 KX250 is phenomenal!”

And while it’s sometimes difficult to improve on a winner, Kawasaki has succeeded in
making the KX250 even better for 2006 by fine tuning the engine, suspension and brakes.
To make this 250 Supercross race winner even quieter, the 249cc, liquid-cooled, twostroke
engine features a new piston profile, while a longer, wider silencer ensures the KX250
meets modern noise emission standards. Plus, the silencer’s all-new, long-fiber packing is more
durable and requires less maintenance. And to keep the KX250 at the best-possible temperature,
a new water pump impeller increases coolant circulation.

Changes to the KX250’s chassis include a strong, lightweight Renthal aluminum
handlebar, and the rear shock now features dual compression adjustability so riders have more
tuning options for both low-speed and high-speed compression damping. Up front, the Kayaba
AOS fork has a new, one-piece sleeve to improve suspension action at full compression.
For 2006, the KX250 has even stronger stopping power. The new petal-style disc brakes
are not only lighter, but their shape helps to clean the brake pads for more efficient braking
performance.

The KX250 also features a new look for 2006, with aggressive new graphics and a new,
two-tone seat.

Kawasaki offers optional parts for the KX250, including carburetor tuning parts, ignition
rotors, a larger countershaft sprocket, aluminum and steel rear sprockets, solid brake discs for
wet racing conditions and a 20-inch front wheel.

FEATURES

Engine
– New piston profile helps to reduce mechanical noise
– Copper-plated steel washer improves cylinder head’s sealing performance
– KIPS® power valve O-ring offers improved sealing performance
– New reed valve stopper features new shape to improve low-rpm response – revised shape improves
scavenging efficiency by facilitating airflow through the third scavenging port
– New water-pump impeller increases coolant circulation for improved high-rpm and over-rev performance
– Primary gear is now secured using a key and lock-nut to help reduce mechanical noise
– New kickstart lever has revised shape and mounting angle for improved durability
– New silencer is slightly wider and nearly two inches longer to ensure the KX™250 meets stricter noise
emission standards
– New long-fiber silencer packing is more durable and requires less maintenance

Chassis
– Renthal aluminum handlebar is strong and lightweight
– Front and rear petal disc brakes help to reduce unsprung weight
– Petal-shaped discs help to clean the brake pads for more efficient braking performance
– Rear shock now features dual compression adjustability so riders have more tuning options for both lowspeed
and high-speed compression damping
– Fine-tuning to the Kayaba AOS (Air-Oil-Separate) fork via a new one-piece plastic sleeve inside the fork
inner tubes improves suspension action at full compression

New Styling
– Aggressive Kawasaki Lime Green and black graphics are matched by a two-tone seat

Options
– Carburetor tuning parts
– Different inertia magneto rotors
– Larger countershaft sprocket
– 20-inch front wheel
– Solid brake discs for wet racing conditions
– Aluminum and steel rear sprockets
– Optional fork and shock springs
– Steel spoke nipples
– Front and rear wheel assemblies

SPECIFICATIONS*
Engine: Two-stroke single with KIPS®
Displacement: 249cc
Bore x stroke: 66.4 x 72.0mm
Cooling: Liquid
Carburetion: Keihin PWK38S with Power Jet
Induction: Piston reed valve
Compression ratio: 10.5 (low speed) – 9.1 (high speed):1
Ignition: Digital CDI
Transmission: Five-speed
Final drive: Chain
Frame: Perimeter style, high-tensile steel with aluminum subframe
Rake / trail: 26 degrees / 4.1 in.
Front suspension / wheel travel: 48mm inverted cartridge-type telescopic fork with 16-way compression and
rebound damping / 11.8 in.
Rear suspension / wheel travel: UNI-TRAK® linkage system with 18-way low-speed compression and 2-turn
high-speed compression damping, plus 16-way rebound damping and fully adjustable spring preload / 12.2 in.
Front tire: 80/100-21 51M
Rear tire: 110/90-19 62M
Front brake: Single semi-floating 250mm petal disc with dual-piston caliper
Rear brake: Single 240mm petal disc with single-piston caliper
Overall length: 86.0 in.
Overall width: 32.1 in.
Overall height: 49.8 in.
Ground clearance: 13.4 in.
Seat height: 38.0 in.
Dry weight: 213.9 lbs.
Wheel base: 58.3 in.
Fuel capacity: 2.2 gal.
Color: Kawasaki Lime Green / Black
MSRP: TBA

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