2008 Kawasaki KX450F

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Refined Power Delivery for Improved Holeshot Performance.

Test ride

I have ridden and owned several bikes and mx bikes over the years and like you, I wanted the best of the best. But let me say WOW! This bike was more than I expected. It turns on a dime, feels light in the air and pulls so hard through the whole band that unless you are a faster that average rider (I’m not) or ride on a very long track, you will not need fourth gear too often. I have only had one issue with this bike thus far. The hot-start lever stuck. I never used it anyway. This bike always starts on the first kick. Not second, not third, but first...always. I have been so pleased with this bike that I would recommend it to anyone interested in buying a 450F. You definitely will not be disappointed with this bike. If you are considering a 450...this is the one.


Who knew I would be so pleased with this machine. The suspension is great. The power is consistent throughout. Cold or hot it usually starts with one kick. Let me tell you...you will not be sorry to own this monster. It’s a sweet ride that when you want it to...can get MEAN! This bike is going to be a major competitor in the 450 ring this year.

2008 Kawasaki KX450F

Kawasaki KX450F

A host of improvements make the 2008 Kawasaki KX450F 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.


Kawasaki KX450F


  • 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


  • 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


  • 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


  • High-capacity Denso radiators deliver superior cooling efficiency
  • Slim radiators feature tightly packed cores and fins designed to enhanced heat dispersion


  • 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

Kawasaki KX450F


  • Front and rear petal disc brakes help reduce unsprung weight
  • Disc shape helps clean the brake pads for more efficient braking performance

Kawasaki KX450F


  • 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

Kawasaki KX450F


  • 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


  • 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


Kawasaki KX450F

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
MSRP: $6,999

Kawasaki KX450F


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