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– 2010 Kawasaki KX250F
2010 Kawasaki KX250F
Factory-style components and tuning for every racer
Kawasaki’s KX’250F motocrosser had a victorious year, winning on the track and topping its class in numerous enthusiast magazine shootouts. The successful mix of the highly rigid aluminum frame and top-shelf suspension components deliver superb high-speed stability, while its chassis geometry and high-revving engine offer excellent rear wheel traction and holeshot-winning performance. Christophe Pourcel used his new Monster Energy/ Pro Circuit / Kawasaki KX250F to win the AMA East Supercross Lites Championship and then continued his winning ways into the outdoor season. But in the volatile world of racing, it’s a constant challenge to stay on top.
To ensure it continues its podium-topping tradition, Kawasaki fine-tuned the light handling KX250F for 2010. The engineers capitalized on its solid foundation, with refinements focused on increasing performance and longevity. The result of their labors will help the KX250F add to its ever-growing trophy collection.
Borrowing from the racing world, the KX250F gets a new piston with a bridged-box bottom making its first appearance in a mass-production machine. The new piston is lighter and stronger. It also has a revised profile with a shorter skirt and shorter piston pin, which reduces reciprocating weight. It also features a revised crown that improves combustion. The cylinder height was raised accordingly to maintain the 13.2:1 compression ratio. Low-rpm performance was bumped up via a new longer head pipe and shorter mid-section on the new, more durable stainless steel exhaust pipe.
The 249cc, liquid-cooled, four-stroke engine received a number of other refinements for 2010, such as electrofusion treatment on the cylinder bore, revised oil pump rotors and a wider big-end bearing to increase engine life.
Its crank web design produces a crankshaft balance factor of close to 60 percent, on par with Kawasaki’s factory racers. The result is reduced engine vibration, smoother power delivery and increased performance in the mid-high rpm range. Tuned to deliver the widest possible torque band, the KX250F engine offers traction in a controllable, class-leading manner from the first crack of the throttle to wide-open at the rev limiter.
Like its bigger sibling, the KX250F received larger, stronger radiators with increased fin and tube pitch that accumulate less mud and provide more consistent cooling. With the extra strength in the new radiators, the reinforcing brackets could be dropped, helping reduce the weight of the entire radiator assembly.
Transmission durability was also raised inside and out. Building upon the achievements of last year, Kawasaki engineers put larger dogs on the third and fourth input gears to help prevent wear, and revised the fourth input gear holding method by eliminating a circlip and washer and changing the shape of the second input gear to reduce thrust clearance. On the outside, the new KX250F crankcases are stronger and thicker with increased material around the engine mount holes. The transmission action and feedback are optimized with its ratchet drive shift mechanism and integrated clutch cable holder into the crankcase.
With its lightweight construction blend of forged, extruded and cast parts, the KX250F’s slim aluminum perimeter frame has the chassis balance and settings race-experienced riders seek. The center of gravity and locations of key items such as the swingarm pivot, output sprocket and rear axle were positioned to best channel the drive from the rear tire into forward acceleration.
For 2010, chassis improvements are primarily focused on delivering sharper cornering performance and an optimized front-to-rear balance for improved suspension composure. To achieve this balance, the race-oriented suspension settings were revised for a more balanced less forward-leaning chassis posture when riding. A new steering stem with lower rigidity helps lighten handling, while also providing smoother fork action and better impact absorption.
These revisions refine the stable damping performance of the KX250F’s Showa twin-chamber fork during long motos and work in conjunction with the updated swingarm, which features a modified cross-section with thinner wall thickness and narrower internal ribs. The Showa rear shock’s new damping settings provide greater stability and less “kicking” on corner entry. New Uni-Trak rear suspension linkage ratios match these new rear shock damping characteristics.
Designed with rider ergonomics in mind, the KX250F bodywork offers riders a slim interface and a natural positioning that make it easier to go fast. The sleek bodywork components include one-piece, dual injected, two-tone black and green plastic shrouds and side number plates. The shrouds were fine-tuned to fit the new radiators while retaining their slender form. For 2010, a thicker and more rigid front fender graces the KX250F. The slim, rider friendly seat with a non-slip top surface and smooth sides provides excellent seated grip and rider mobility, and gets firmer urethane foam to hold its shape longer.
Chassis protection is grade-A for 2010, and helps sustain the KX’s durability factor. Examples include the large, resin skid plate, the rear caliper guard and the narrow, long-lasting chain guide, all of which offer protection without high weight.
The rest of the KX250F is equally impressive, with premium-quality Renthal aluminum handlebars included as standard equipment along with black triple clamps, engine covers and hubs. The new black alumite coated lightweight aluminum wheels feature a revised cross section that offers both increased strength and lighter weight, and the ribless rear hub and butted spokes further reduce unsprung weight. Factory-style graphics finish off the package and complement the KX250F’s stellar on-track performance.
Racers who ride their KX250F 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 throughout the United States, 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.
Already ranked at the top of its class in numerous enthusiast magazine shootouts, further fine-tuning of the KX250F’s engine and chassis ensures its winning performance is maintained for 2010.
Authentic Kawasaki Accessories are available through Kawasaki dealers.
Features and Benefits:
All-new Engine higher performing and more durable
– 249cc, liquid-cooled, four-stroke, four-valve, DOHC engine delivers hard-hitting power from mid- to high-rpm
– Engine oil capacity decreased from 1.5L on previous model to 1.3L, reducing overall weight and mechanical losses
New Top End
– New cylinder head has revised intake ports for improved performance at all rpm, especially in the high-rpm range
– Special coating applied to the intake port cores during the casting process gives the intake ports extremely smooth surfaces and increased intake efficiency across the rev range
– Head gasket now silicon coated for improved sealing
– New cam chain tensioner spring reduces mechanical loss by approximately 30 percent
New Intake and Exhaust Valves
– Formed from a new, highly rigid, titanium material, the lightweight 31mm intake and 25mm exhaust valves reduce reciprocating weight and offer greater high-rpm reliability
– Ultra-strong valves have extremely thin valve stems on par with those found in supersport machines with the intake valves featuring 0.25mm thicker heads for increased strength
New Titanium Exhaust Pipe
– Tapered, expanding from approximately 35 to 45mm for better throttle response and performance at all rpm
– New silencer body shape to meet 99dB AMA noise regulations
New Crankshaft Balance
– A revised crank web significantly increases the crankshaft balance efficiency; it’s now on par with the factory racers
– Results in reduced engine vibration, smoother power delivery and increased performance in the mid-high rpm range
– New 6.4mm wider radiators have a 6 percent larger capacity than previous model
– Very slim, high-capacity Denso radiators feature tightly packed cores and a fin design deliver superior cooling efficiency for excellent heat dispersion
– Radiator louvers increased from three to four and decreased in size and angle for less overlap and higher air flow
– Revised cylinder head water jacket routes coolant via the front of the cylinder head for a more even cooling performance
– Ratchet drive shift mechanism replaces the previous models gear driven system for improved shift feel and durability
– Improved feel at the clutch lever by integrating the clutch cable holder with the crankcase
– Increasing the interval between gear shafts 1 mm further allows stronger gears to be used
– KX450F type crankcase oil filter added
– Relocated scavenge oil filter screen (with new shape) can be accessed without splitting the crankcases, facilitating easier maintenance
– New clutch and generator covers for increased rigidity and better crash survivability
New Aluminum Perimeter Frame
– Frame has a new 6 mm slimmer overall width main spars shape – narrowing near the bend below the seat for a riding position, then widening at the ankles to offer better grip
– Newly designed main, lower and gusset pieces around the fuel tank with revised cross sections
– Rigidity increased by moving upper engine mounts to sides of the head cover
– New design is 2.2 lbs lighter than previous model
– Weight savings and rigidity balance aided by down tube with a smaller cast bracket that’s now formed via a swaging (squeezing and hammering) process
– Swingarm pivot is located higher in the frame for improved rear wheel traction
– Sub-frame is 1.3 pounds lighter via larger diameter tubing with thinner walls, yet still provides a secure mounting for the new silencer
New Aluminum Swingarm
– New tapered “D” shaped cross section design is 5mm taller at the front (up from 74 to 79mm) and 2 mm shorter at the rear (down from 60 to 58mm)
– Features a new cross bracket design
– Provides a 0.9 lbs weight savings over the previous model
– Alloy swingarm uses a cast front section, tapered hydroformed spars and forged chain adjusters
– Uni-Trak rear suspension system mounts the suspension arm below the swingarm, allowing a longer rear suspension stroke and more precise tuning
– Design improves stability, rigidity and rear wheel traction
New Front Fork
– Showa twin-chamber fork keeps oil and air in separate chambers for stable damping performance during long motos
– Super-hard titanium coating on the outer surface of the inner fork tubes reduces stiction and improves suspension action. The increased surface hardness of the dark navy blue coating also helps prevent scratches and damage to the tubes
– Friction-reducing Kashima Coat on the inside of the outer fork tubes contributes to smoother suspension action, especially during the initial part of the stroke
– Ideal rigidity balance via increased rigidity in the reshaped upper triple clamp and decreased rigidity of the outer fork tubes
– Offset decreased from 24.5mm to 23.5mm, which combined with the frame’s revised rigidity balance and revised suspension settings, helps produce lighter handling
– Enlarged, wrap around black fork tube guards provide greater protection for the inner tubes
– Revised race-oriented suspension settings offer all-around performance improvement
New Rear Shock
– New Showa rear shock features a revised layout and revised damping characteristics for improved performance
– Better response and improved feeling, even when fully-bottomed
– Features Kashima Coat on the tank cylinder for reduced friction and smoother suspension action
– Rear shock features dual compression adjustability, allowing high-speed and low-speed damping to be tuned separately
– Easier accessibility for tuning
New Skid Plate
– Resin material offers greater protection without a weight increase
New Chain Guide
– More slim and compact, down from 42.7 to 34mm wide, with 2mm thicker wear pad
– Reduced weight and longer wear
Improved Rider Interface and Styling
– Foot peg width (front to rear) increased from 46mm on previous model to 50mm for improved feel
– All-new body work and graphics
– New dual injected 2-tone, one-piece plastic shrouds and side number plates
– Right side panel has an added passageway to aid in cooling the silencer
– Black plastic covers, triple clamps, number plates, and engine covers
– Rims are coated in black alumite just like the factory racers
– New seat design that’s slimmer with firmer urethane for improved ergonomics and feel
– Seat has a slip-resistant top surface for good grip when seated and smooth sides for excellent rider mobility
– Larger front brake lever boot offers increased protection against dust
– Clutch cable boot features a large quick adjuster, for easy clutch cable play adjustment on the fly
– Throttle grip has a one-piece collar that provides additional stability during throttle operation
– Lightweight short-length grips feature a pattern designed to provide excellent grip
– Rear caliper guard protects the caliper from damage
– Ribless rear hub and butted spokes reduced unsprung weight
2010 Kawasaki KX250F Technology
A hot start system gives quick starts when the engine is hot. The hot start lever is unitised with the clutch lever.
NEW – Increased spring set load for the auto-decompressor located on the exhaust cam shaft contributes to easier starting
Additional performance-oriented engine characteristics
The engine was tuned such that the torque curve follows the limit of running resistance for as long as possible.(Unchecked, engine torque can exceed this limit, resulting in wheel spin, which does nothing to help forward momentum.)
Efforts were made to achieve the widest possible torque band, so that traction efficiency would be maximized for a greater part of the rev range.
Lightweight titanium valves (IN: 31mm; EX: 25 mm) reduce reciprocating weight and offer high-rpm reliability. The ultra-light valves have extremely thin valve stems on par with those found in supersport machines. The intake valves feature thicker heads for increased strength and both intake and exhaust valves are formed from a new, highly rigid, titanium material.
Crank web design increases offsetting moment for a high crankshaft balance factor. At close to 60%, the balance factor of the ’10 KX250F is on par with our factory racers. The result is reduced engine vibration, smoother power delivery and increased performance in the mid-high rpm range.
Sprocket-style chain drive roller helps smooth engine braking by reducing the effect of driveline lash when the rider gets off the gas quickly and play in the lower side of the chain suddenly tightens. The additional control facilitates corner entry.
NEW – Large synthetic skid plate offers great protection with minimum weight.
NEW – Revised front fender is thicker and more rigid.
NEW – New chain with thinner inner links offers offers 20g in weight savings.
Factory-style chassis components and tuning
The KX250F’s slim aluminum perimeter frame is a lightweight construction composed of forged, extruded and cast parts. Chassis balance and settings were all set to suit race-experienced riders. The centre of gravity and key dimensions (swingarm pivot, output sprocket and rear axle locations) were chosen so that the rear tire would drive the bike forward (instead of causing it to squat). For ’10 revisions to the swingarm and suspension components were designed to offer greater cornering performance, optimized front-rear balance and greater stability on corner entry thanks to reduced “kicking” (tendency of an overworked rear shock to cause the seat to rise, hitting the rider in the rear).
NEW – New steering stem shaft with lower rigidity contributes to lighter handling.
NEW – Swingarm with revised cross-section, wall thickness and internal ribs contributes to improved cornering performance, enabling lighter turn-in and tighter cornering.
The alloy swingarm uses a cast front section, tapered hydroformed spars and forged chain adjusters.
Showa twin-chamber fork keeps oil and air in separate chambers for stable damping performance during long motos.
NEW – Revised settings for ’10 optimize the front/rear balance, resulting in a flatter (less forward-leaning) chassis posture when riding. Further, revised damping settings and a less rigid steering stem offer improved action(smoother) and increased absorption performance.
A super-hard titanium coating on the outer surface of the inner fork tubes reduces sliding friction (and stiction) and improves action, contributing to the smoother ride. The increased surface hardness of the dark navy blue coating also helps to prevent scratches and damage to the tubes.
Friction-reducing Kashima Coat on the inside of the fork outer tubes contributes to smoother suspension action (especially at the initial part of the stroke) and a better ride feel.
NEW – Revised shock damping settings offer increased absorption performance, reducing the chance of “kicking” for easier corner entry.
The rear shock features dual compression adjustability, allowing high-speed and low-speed damping to be tuned separately.
The rear shock also features the Kashima Coat on the tank cylinder. The reduced friction smoothes suspension action.
NEW – New piston (like that of the 2010 KX450F) features the same design used on our factory racers. A revised profile with a shorter skirt, reinforced external ribs and the first mass-production use of a bridged-box bottom, featuring fully flush internal bracing, results in a lighter, stronger piston.
NEW – Shorter piston pin contributes to reduced reciprocating weight.
NEW – A revised piston crown contributes to improved combustion.Cylinder height increased accordingly to maintain compression ratio at 13.2:1.
NEW – Exhaust pipe dimensions revised (non-tapered part is longer), for increased low-rpm performance.
Factory-style and other race-oriented components
Among the KX250F’s numerous factory-style components are its front and rear petal disc brakes. In addition to helping reduce unsprung weight, the wave shapes of the petal discs help clean the brake pads for more efficient braking performance.
New Revised rear brake pad material offers stronger braking performance.
Rear caliper guard protects the caliper from damage.
A factory-style Renthal (standard-type) aluminum handlebar is standard equipment.
Rib-less rear hub and butted spokes reduced unsprung weight.
New rim design with revised cross section offers both increased strength and lighter weight.(F: -20 g; R: -60 g)
Rims are coated in black alumite – just like our factory racers.
Factory-style graphics complement the KX250F’s highly tuned performance.
Modifications for enhanced durability and reliability
NEW – Electrofusion treatment on cylinder bore results in a surface with good oil retention. Further, the molybdenum on the surface of the cylinder bore helps resist scorching, contributing to durability.
NEW – Wider (18mm >> 19 mm) big-end bearing featuring thicker copper plating on its cage, and a longer crank pin offer increased reliability.
NEW – Revised oil pump rotors offer increased reliability and durability. Feed pump rotor size is larger (5 mm >> 5.5 mm), increasing oil flow; scavenge pump rotor is smaller (11 mm >> 10.5 mm), reducing mechanical loss.
NEW – Larger dogs on the 3rd and 4th input gears help prevent wear, and revising the 4th input gear holding method (by eliminating a circlip and washer and changing the shape of the 2nd input gear) reduces thrust clearance. These changes offer increased shifting reliability.
NEW – Crankcases with revised engine mounts and increased thickness are stronger, contributing to enhanced durability.
NEW – New thicker (22 mm >> 32 mm), wider (113.8 mm >> 117.8mm)radiators with increased fin and tube pitch are stronger, offer better resistance to mud build-up, and maintain cooling performance. Because the new radiators are stronger, reinforcing brackets could be eliminated, resulting in lower overall weight. (These radiators feature the same construction as those on the 10MY KX450F.)
NEW – Exhaust pipe’s new stainless steel construction is more durable. Revised joint between the exhaust pipe and muffler offers increased sealing performance. Rubber damper collar used for the rear silencer mount also contributes to increased durability.
Designed with rider ergonomics in mind, bodywork components offer the rider a slim interface, the natural position making it even easier for racers to go fast.
NEW – Formed using a double-injection moulding process, the 2-tone shrouds contribute to the slim package. Fine-tuned to accommodate the new radiators, the shrouds feature a slightly slimmer design.
2-tone side covers are also formed using a double-injection moulding process. Like the shrouds they contribute to the slim package. A hole in the right-side cover helps cool the silencer.
The frame widens at the ankles to offer the rider better grip and narrows near the bend below the seat to allow a slim riding position.
NEW – Slim seat features firmer urethane which keeps its original shape longer.
The seat uses a slip-resistant top surface for good grip when seated and smooth sides for excellent rider mobility.
Wide (front-to-rear) footpegs designed to offer grip and superb feel at the pegs.
The clutch cable boot features a large quick adjuster, making it easier for riders to adjust play in the clutch cable.
Throttle grip has a unitised collar. The one-piece unit provides additional stability during throttle operation.
Lightweight short-length grips feature a pattern designed to provide excellent grip.
Optional engine parts include magneto rotors with different inertias (3.6, 4.8 kg cm2; STD: 4.4 kg cm2) and a 12T output sprocket (STD: 13T).
Optional chassis parts include handlebar holder for a Ã¸28.6 mm bar (STD: Ã¸22.2mm), aluminum and steel rear sprockets (46-50T; STD: 48T), solid petal brake rotors for wet races, different springs for the front fork and rear shock, and manual decompression lever & cable.
2010 Kawasaki KX250F – USA Specifications
MSRP $6,999 USD
Engine: Four-stroke single with DOHC and four valves
Bore x stroke: 77.0 x 53.6mm
Carburetion: Keihin FCR37 and hot start circuit
Compression ratio: 13.2:1
Ignition: Digital CDI with K-TRIC throttle position sensor
Transmission: Five-speed with wet multi-disc manual clutch
Final drive: Chain
Frame: Aluminum perimeter
Rake / trail: 27.4 degrees / 4.7 in.
Front suspension / wheel travel: 47mm inverted Showa twin-chamber telescopic fork with 16-way compression and rebound damping / 12.4 in.
Rear suspension / wheel travel: UNI-TRAK linkage system and Showa shock with 13-way low-speed and stepless high-speed compression damping, 17-way rebound damping and fully adjustable spring preload / 12.2 in.
Front tire: 80/100-21
Rear tire: 100/90-19
Front brake: Single semi-floating 250mm petal disc with dual piston caliper
Rear brake: Single 240mm petal disc with single-piston caliper
Overall length: 85.4 in.
Overall width: 32.3 in.
Overall height: 50.0 in.
Wheelbase: 57.9 in.
Ground clearance: 13.4 in.
Seat height: 37.6 in.
Curb weight: 231.4 Lbs.
Fuel capacity: 2.1 Gal.
Color: Lime Green
*Note: Specifications and pricing are subject to change.
2010 Kawasaki KX250F – Canada Specifications
MSRP: $8,499 CDN
Type Liquid-cooled, 4-stroke Single
Displacement 249 cc
Bore and Stroke 77.0 x 53.6 mm
Compression Ratio 13.2:1
Fuel System Carburetor: Keihin FCR-MX37
Valve System DOHC, 4 valves
Ignition Digital AC-CDI
Starting Primary kick
Lubrication Forced lubrication, semi-dry sump
Transmission 5-speed, return
Final Drive Chain
Primary Reduction Ratio 3.350 (67/20)
Gear Ratios: 1st 2.142 (30/14)
2nd 1.769 (23/13)
3rd 1.444 (26/18)
4th 1.200 (24/20)
5th 1.045 (23/22)
Final Reduction Ratio 3.692 (48/13)
Clutch Wet multi-disc, manual
Type Perimeter, aluminum
Wheel Travel: Front 315 mm
Wheel Travel: Rear 310 mm
Tire: Front 80/100-21 51M
Tire: Rear 100/90-19 57M
Caster (Rake) 27.4°
Trail 118.6 mm
Steering Angle (left/right) 42° / 42°
Front: Type 47 mm inverted twin-chamber telescopic fork
Compression Damping 16-way
Rebound Damping 16-way
Rear: Type New Uni-Trak
Compression Damping 13-way (low-speed), 2-turns or more (high-speed)
Rebound Damping 17-way
Spring Preload Fully adjustable
Front: Type Single semi-floating 250 mm petal disc
Rear: Type Single 240 mm petal disc
Overall Length 2,170 mm
Overall Width 820 mm
Overall Height 1,270 mm
Wheelbase 1,470 mm
Ground Clearance 340 mm
Seat Height 955 mm
Curb Mass 105.0 kg (231.5 lbs)
Fuel Capacity 8 litres
Colour Lime Green with factory-style graphics
The specifications mentioned here apply to and have been achieved by production models under standard operating conditions. We intend only to give a fair description of the vehicle and its performance capabilities but these specifications may not apply to every machine supplied for sale. Kawasaki Heavy Industries, Ltd. reserves the right to alter specifications without prior notice. Equipment illustrated and specifications may vary to meet individual markets. Available colours may vary by market.