Introduction
Refined Power Delivery for Improved Holeshot Performance
A host of improvements make the 2008 Kawasaki KX™450F motocrosser
easier to ride and more reliable than ever. A newly-revised powerplant
and improved shifting highlight the improvements made to the
dominant AMA and World Supercross GP Championship winner.
With little doubt about the ample power of the KX450F, the 2008
engine received smoother, more user-friendly and linear low-rpm
throttle response and torque delivery. These changes result in
reduced fatigue, allowing riders to go faster for more laps.
The improvements were achieved with new wedge-shaped crank webs,
combined with a new heavier flywheel, resulting in reduced engine
vibration and better low-end performance. Reliability of the
engine was enhanced via a new connecting rod material with a
harder surface, a revised gear ratio and rotor on the oil pump
for increased oil circulation and the piston-cooling oil jet
was redesigned to prevent oil from being trapped under the piston.
The bottom end changes are coupled with a new shift cam shape
and a wider track on the shift drum to permit easier and more
consistent gear selection in the KX450F's five-speed transmission.
An ultra-smooth coating on the intake ports improves intake efficiency
and throttle response, while revised ignition data provides easier
restarting and a new five-bolt oil pump cover round out the engine
upgrades.
Already a great handling motorcycle, the 2008 KX450F further
benefits from new engine mounts spaced 10mm farther from the
engine. This allows a slight decrease in torsional frame rigidity
making for quicker turning and increased rear wheel traction.
Complementing the chassis change, the Kayaba fork and shock settings
were fine-tuned to improve the front / rear balance for quicker
turning and slightly stiffer settings were made to improve the
bottoming characteristics. The overall suspension action is even
smoother now through the addition of the friction-reducing Kashima
Coat treatment on the inside surfaces of the outer fork tubes
and the shock reservoir.
The 2008 KX450F will be available in Kawasaki lime green, with
new black alumite-coated rims for a factory appearance, and aggressive
graphics.
 |
 |
|
|
Features
Engine
- 449cc liquid-cooled, DOHC, four-stroke single with lightweight,
oxidized membrane treated titanium valves
- High-acceleration cams help the engine rev quickly
- Revised piston-cooling oil jet
- Fifth bolt added to oil pump cover for improved sealing
- Dual overhead, lightweight camshafts feature a soft-nitride
surface treatment for long wear and high-rpm reliability
- Special coating on the intake ports improve intake efficiency
at all rpm
- Titanium 36mm intake and 31mm exhaust valves with aluminum
spring retainers and dual, progressive valve springs reduce reciprocating
weight and cylinder height and help ensure reliable valve control
at high rpm
- Maintenance free screw-type automatic cam chain adjuster
- Low-friction coating on piston skirt
Bottom End
- New connecting rod material has a harder surface for reduced
friction
- New wedge-shaped crank web combined and a new heavier flywheel
to reduce engine vibration and increased low-end performance
- Oil pump has a revised gear ratio and 2mm larger rotor to increase
oil flow
- Unique crankcase breather system vents through the balancer
shaft located in the crankcase, permitting the engine to rev
more freely
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 provides easier starts when the engine is
hot, and the hot start lever is unitized with the clutch lever
Exhaust
- New muffler joint bracket and thicker baffle plate help increase
reliability
- Large 41mm titanium exhaust header for increased power
- Light weight, tapered head pipe with titanium heat shield helps
increase exhaust efficiency over a broad rpm range
- Silencer uses long-fiber packing for lower maintenance
Cooling
- High-capacity Denso radiators deliver superior cooling efficiency
- Slim radiators feature tightly packed cores and fins designed
to enhanced heat dispersion
Shifting
- The five-speed transmission received a new cam shape and a
wider track (5.0mm to 6.5mm) on the shift drum to permit easier
and more consistent gear selection
Brakes
- Front and rear petal disc brakes help reduce unsprung weight
- Disc shape helps clean the brake pads for more efficient braking
performance
Frame
- New engine mounts moved 10mm farther from the engine for a
slight decrease in torsional frame rigidity to quicken turning
and increase rear wheel traction
- All-aluminum perimeter frame is a 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
- Works-style aluminum skid plate and plastic engine guards
Front Suspension
- Kayaba AOS (Air-Oil-Separate) fork keeps oil and air in separate
chambers for stable damping performance during long motos
- New friction-reducing Kashima Coat treatment added on the inside
surface of outer fork tube
- DLC (Diamond Like Coating) on the fork sliders reduces stiction
Rear Suspension
- UNI-TRAK® rear suspension system features revised shock
valving to maximize traction for better front/rear balance, acceleration
and enhanced controllability
- The shock now features dual compression adjustability, for
separate high- and low-speed damping tuning
- A single, large port into the adjuster improves rider feel
and adjustability over previous twin adjusters
- New friction-reducing Kashima Coat treatment added on the inside
of shock reservoir
- Alloy swingarm uses cast front section, tapered hydroformed
spars and forged chain pullers; the tapered spars are shaped
to provide a balance of flex and rigidity required of the aluminum
frame
- Sprocket style chain roller reduces drive lash
Wheels
- 32-spoke rear wheel for reduced unsprung weight
- Lighter and stronger rear hub for increased durability and
less unsprung weight
- New black alumite-coated rims for a factory appearance
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
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
Options
- Different weight magneto rotors (+/-1 kg.cm2)
- Handlebar Holder for a 1 1/8 in. bar (STD: 7/8 in.)
- Aluminum and Steel Rear Sprockets (+/-2T)
- Solid Petal Brake Rotors for wet races
- Optional Rate Fork and Shock Springs
- 20" Front Wheel
- Manual Decompression Lever & Cable
|
|
|
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: 12.0:1
Carburetion: Keihin FCR40
Ignition: Multi-map digital CDI with throttle position sensor
(K-TRIC)
Transmission: Five-speed
Rake / trail: 27.1 degrees / 4.6 in.
Front suspension / wheel travel: 48mm inverted, Kayaba AOS with
DLC coated sliders, 22-position compression and 20-position rebound
dampening adjustment / 12.4 in.
Rear suspension / wheel travel: UNI-TRAK® linkage system
and Kayaba shock with 22-position low-speed and stepless high-speed
compression dampening, 22-position rebound dampening and fully
adjustable spring preload / 12.4 in.
Front tire: 90/100-21
Rear tire: 120/80-19
Front brake: Semi-floating 250mm petal disc
Rear brake: 240mm petal disc
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 lbs.
Fuel capacity: 1.9 gal.
Color: Lime Green
* Price and specifications subject to change
|
|
|
|
