KX450F motocross

Kawasaki, the brand that introduced the motocross world to perimeter frames and awe-inspiring 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 all-new 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 slip-resistant 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.

Those who race 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, 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.

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: 27.1 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 low-speed and 2-turn
high-speed compression dampening, 22-way rebound dampening and
fully adjustable spring preload / 12.4 in.
Front tire: 90/100-21 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: 86.0 in.
Overall width: 32.3 in.
Overall height: 50.4 in.
Wheelbase: 58.5 in.
Ground clearance: 13.6 in.
Seat height: 38.0 in.
Dry weight: 220.1 lbs.
Fuel capacity: 1.9 gal.
Color: Kawasaki Lime Green / Black

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
- New UNI-TRAK® rear suspension system features linkage ratios to suit the new frame 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

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