- Liquid-cooled, four-stroke single with DOHC and four valve cylinder head
- Horsepower @ RPM:
- 53.92 hp @ 8,500 rpm
- 43mm Keihin Throttle body Fuel Injection
- 449 L
- Top Speed:
- 120 mph
The 2010 Kawasaki KX450F is now a fact on dealership floors and it comes with a whole range of improvements that are more than enough for a review of this new model year. Like with all previous generation models, the goal here was to improve performance and reliability as well as rider comfort and looks.
Kawi is quite proud of their new KX450F and they have plenty of reasons to also be enthusiastic about the new racing season. You see, more power and less weight will always do the trick in the right hands.
Revising their high-end motocross model, Kawasaki engineers covered every single aspect of the bike. We’ll start with the front end and mention that they changed the damping and the spring rates of the front fork, which features the Kashima Coat on the inside of the fork outer tubes and the Diamond-Like Carbon (DLC) coating on the outer surface of the inner fork tubes. By doing so, friction is seriously reduced and the fork’s performance is very smooth. This also characterized the 2009 model year’s fork, so at least we know it proved efficient.
The Kayaba rear shock features a large 50mm piston, high and low rebound adjustability, compression adjustability and also Kashima Coat treatment on the cylinder for reduced friction and smoother suspension action. Spring rate and damping settings have also been revised.
Kawasaki claims to have lightened the new KX’s handling by using a new steering stem shaft and until we actually get on the bike we’re not at all underestimating the Greens.
By simply improving the fork action and sharpening handling, the 2010 Kawasaki KX450F starts to sound like a greater bike already. But the engine’s midrange performance was also seriously improved due to the use of a new Programmable ECU. All riders have the possibility to set the bike to work according to their riding demands, which is a nice thing to have on a machine that you plan to ride to the very limit.
The actual engine gets a new crankshaft with more internal inertia for
53.92 hp fuel-injected single-cylinder engine
improved traction and low-end performance, new camshaft and, most importantly, a Bridged-Box Bottom Piston (just like on Kawasaki racing dirt bikes). The fact that this piston is both lighter and stronger improves the motor’s performance, but also had much to do with the new, thicker and taller radiators and the 40mm shorter header pipe than on the 2009 model.
While the transmission case was only strengthened, the clutch is totally new (the new operating plate improves oil flow and the friction plates feature approximately 75% more friction material). Sounds like this piece will resist well to fatigue!
The seat of the 2010 model has been changed. It is now made of firmer urethane foam for proper ergonomics and durability. Also, the 50mm footpegs and the fact that the frame is wider at the rider’s ankles put him in total control of the bike. We shouldn’t forget about the stock Renthal handlebar either.
At the back, the rear brake pad material lasts longer and offers more performance, which is a nice thing to hear about, considering that nobody will ever ride this new KX450F slow.
Kawasaki’s all-new, 2006 KX450F may have been considered a late arrival, but ever since it was launched, the Green motocrosser managed to keep up with the strong players in this business and now with motorcycles such as the notorious Honda CRF450R , Yamaha YZ450F and Suzuki RM-Z450 . Also, we shouldn’t forget about contenders from the old continent. These are the Husqvarna TC450 and KTM’s 450 SX-F .
In terms of shape, we notice that the bike is actually very similar to the Monster Energy version, which is still stuck in 2009. It comes with dual injected two-tone, one-piece plastic shrouds and side number plates, while the dominating color is Lime Green. Still, we do notice a more aggressive overall touch and the bike is actually more compact and appealing.
The two-tone seat dictates the black/green half of the shrouds, while both fenders are green and the mudguards and rims are all black. Just like on all motocrossers, this one’s number plates are white, but not for long.
We appreciate the fact that there’s not that much height difference between the 38-inch seat and the fuel tank. This allows riders to position themselves closer to the tank and so gain more control over the light machine (250.4 pounds). Even so, last year’s Monster Energy version had a curb weight of only 247.2 pounds and the same aggressive (if not even more aggressive) shape. This model stands out thanks to the Ebony color scheme.
“…make no mistake about it, the Kawasaki is fast. It makes a ton of power in the middle and on top. The new bike is even faster than the old one, and that verges on being too much to handle. We never asked for a bike with more snap, but we did want a longer interval between piston changes.” – dirtbikemagazine
“…what really makes the KX450F a nice ride is the chassis. The DLC (Diamond-Like Carbon), AOS (Air-Oil Separate) Kayaba fork and new shock, swingarm and linkage provided a plush ride on what was, okay, a smooth, well-prepped track.” – cycleworld
“The chassis felt a lot better. It felt a lot more like a 250F in the sense that the back-end felt like it sat lower. It was way more comfortable to ride. The rear end tracked better and it wasn’t dancing around so much.” – motorcycle-usa
“The 2010 Kawasaki KX450F is probably the fastest 450 in the class. I’m saying that completely blind since it’s the only 2010 450 Motocross bike I’ve ridden but after one twist of the throttle on this green monster it’s not that strange of an assumption.” – dirtrider
“The bike has power. No, make that power. It has a good amount of low-end and a massive midrange hit. Top-end pull was excellent.” – motorcycle
“The 2010 Kawasaki KX 450F provides an ideal platform for riders looking to win races. Its precise aluminum frame, premium suspension components and expert-tuned settings are designed to deliver superb high-speed stability, enabling racers to capitalize on its amazing engine performance.” – motocross
“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% of the crankshaft’s reciprocating weight, producing an effective "counterweight" effect.” – cyclenews
Dealers are most likely waiting for the previous generation Monster Energy version to sell out before bringing in the new models and the $7,749 MSRP does help, given the fact that a 2010 Kawasaki KX450F starts at $8,049.
Kawasaki didn’t radically upgrade the KX450F for 2010, but neither the bike needed it, given the results from previous years it spent on the track. Instead, they’ve covered all of the aspects required to keep it among the most competitive 450s out there, which is what all manufacturers follow.
Engine and Transmission
- 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 Injection: 43mm Keihin Throttle body
- Ignition: Digital DC-CDI
- Transmission: Five-speed
Chassis and Dimensions
- Rake / trail: 26.7 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 50mm piston, 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: 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: 58.3 in.
- Ground clearance: 13.4 in.
- Seat height: 38.0 in.
- Curb weight: 250.4 lbs.
- Fuel capacity: 1.9 gal.
Features & Benefits
At a glance
- More Powerful Engine
- Revised Suspension Settings
- Refined Fuel Injection
- Still Super-Easy to Start!
- 449cc liquid-cooled, DOHC, four-stroke single
- Cylinder skirt strengthened to handle increased engine performance
- Right-side crankcase reinforced at lower engine mount for increased strength and durability
- A forward lean angle of 3 puts the engine in the ideal position for maximum traction
- Tuned for a broad powerband with the torque curve set just under the wheel spin threshold
- High-acceleration cams help the engine rev quickly
- Maintenance free screw-type automatic cam chain adjuster
- Large flap inside the airbox helps prevent the ingress of mud and water
New Bridged-Box Bottom Piston
- First mass-production use of a bridged-box bottom piston design
- Same design as used on our factory racers, offers improved performance at all rpm
- 7 grams lighter than the 09 piston
- 6mm shorter piston skirt features a 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
- Shorter piston pin has a smaller inner diameter for increased strength
- New intake camshaft features a revised sprocket/shaft arrangement which advances intake valve timing by two degrees, to suit revised engine characteristics
- 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
- New crankshaft with a slightly higher inertial mass helps boost rear wheel traction
- Wedge-shaped crank web provides enough offsetting moment for a 60 percent balance factor this is similar to the crank balance in Kawasaki’s factory race engines
- End result is 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 power stability when jumping/landing
- Ultra-fine atomizing injector with 12 holes sprays particles with a droplet size of 60 for smooth power deliver and smooth 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, the optimum angle for mid-range power
High performance ECU
- New ECU programming and revised settings offer improved response at low-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
Lightweight Aluminum Fuel Pump
- Located in the fuel tank
- 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
- Fuel return hose from the pressure regulator helps ensure there is always fuel in the inlet port, preventing stalls due to fuel splashing and enabling riders to use all the fuel
- 1.8 gallon fuel tank is formed using a rotational molding process
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 preference it is not necessary to re-tune, no changing needle jets to suit climatic conditions like on a carbureted model
- 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.
- 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
- New radiators are 10mm taller and 7.6mm wider, with increased fin and tube pitch to provide a extra strength and better resistance to mud build-up
- High-capacity Denso radiators feature tightly packed cores and a fin design that delivers superior cooling efficiency
- Because the new radiators are stronger, reinforcing brackets could be eliminated, resulting in lower overall weight
- New shrouds feature a slightly slimmer design that is fine-tuned to accommodate the new radiators
- Radiator louvers feature four small blades set at a shallow angle, for minimum overlap and maximum air flow
- New clutch provides a more direct feel and increased control
- Material trimmed from the spring holders and outer surface of the plate, to optimize rigidity and improve oil drainage, contributing to more direct feel
- Friction plates feature approximately 75% more friction material, contributing to a more direct feel
- Operating plate pusher features an increased outer diameter, to reduce 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
- New chain with thinner inner links offers 20g weight savings
- Sprocket-style chain drive roller reduces the effect of driveline lash, helping smooth engine braking and facilitating additional corner entry control
- One-piece stainless steel exhaust pipe is 40mm shorter than the 09 unit, contributing to improved mid-high rpm performance
- Optimized exhaust routing contributes to improved ergonomics
- High volume silencer body helps meet noise regulations - currently 99dB
- Right side panel has special passageway to help cool the silencer
Powerful Disc Brakes
- Revised rear brake pad material offers stronger 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
- New steering stem shaft with lower rigidity contributes to lighter 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 down tube that is now formed with a swaging (squeezing and hammering) process
- Swingarm pivot is located high in the frame to maximize rear wheel traction
- Revised cross-section contributes to lighter 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
- Revised Uni-Trak rear suspension linkage ratio increases rear traction performance
- Suspension arm is mounted below the swingarm, to allow a longer rear suspension stroke and more precise tuning
- Race-oriented suspension settings offer maximum over-all performance
- Revised spring rate and damping settings work with the less rigid steering stem to 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 outer tubes contributes to smooth suspension action (especially at the initial part of the stroke) and a superb ride feel
- Wrap around black fork tube guards offer effective protection for the inner fork tubes
- New spring rate and damping settings contribute to increased stability and improved impact performance when landing 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 2-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 foot pegs 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 which 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 smooth sides for excellent rider mobility
- 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 while on the fly
- Rear caliper guard helps protect the caliper from damage
- Ribless rear hub and butted spokes offer light weight and excellent durability