2021 KX250



The KX design philosophy – Put mid-level to expert riders on the top step of the podium. Designed to continue the KX250 history of winning – in the extremely competitive 4-stroke 250cc class Kawasaki race machines have the most AMA Supercross and Motocross titles – the 2021 model KX250 builds on the engine changes from the previous year to deliver even greater power and an even higher rev limit, plus electric start and a hydraulic clutch.


  • Fuel-injected 249cm3 liquid-cooled 4-stroke, single cylinder engine.
  • New slim, ergonomic bodywork KX450 styling with long, smooth surfaces and flatter tank-seat line.
  • Revised, KX450-based frame and KX450 Swingarm offer improved handling and increased rear wheel traction.
  • Fitted with a KX450 Hydraulic Clutch offering more direct feel and light lever action for more consistent feeling.
  • Updated Fine-Tuned Suspension and Brake Components for increased bump absorption and traction.
  • Ease of use with Electric Start and lightweight compact Li-ion battery.
  • Holeshot advantage with Launch Control Mode.
  • High performance KYB 48mm dia inverted coil-spring fork (with Kashima Coat) matched to a new KYB shock unit.
  • Factory-style 28.6mm Renthal Aluminium Fatbar reduces vibration and shock transmitted to the rider.



The KX250 was the first mass-production motocrosser to feature Showa’s Separate Function front Fork (SFF), which separates damping and shock absorption duties:

  • Left fork tube: damping assembly
  • Right fork tube: spring

The configuration offers both smooth action and firm damping performance – a combination difficult to achieve with a conventional fork.

  • Using large φ48 mm inner tubes contributes to greater fork rigidity, resulting in a more planted feel from the front wheel.
  • With only one spring, the friction generated between the spring(s) and fork inner tube(s) is greatly reduced (approximately 25% less), resulting in extremely smooth action throughout the fork stroke.
  • Being able to use larger damper pistons not only enables smoother action, it also makes firm damping performance possible.
  • The large diameter fork tubes enable larger damper components.
    Main piston diameter         30 mm
    Sub-piston diameter          35 mm
    With the large components, the same damping force as the 47 mm SFF Type 1 can be achieved with a lower internal pressure. With the lower pressure, the 48 mm SFF Type 2 is even better equipped to offer both increased riding comfort and firmer damping performance.

.Low friction Titanium hard coating on the SFF Type 2 Forks.


A super-hard titanium coating on the outer surface of the inner fork tubes helps prevent wear abrasion.  The fork’s surface hardness of the dark navy blue coating also helps to prevent scratches and damage to the tubes.  Because the surface remains smooth for a longer period, sliding friction (and stiction) is reduced and action is improved, contributing to a smoother ride. (The KX250 is the only motocrosser in its class to feature this race-ready coating standard.)


Removing the damper assembly from the right fork tube frees up space for a pre-load adjuster. Having a preload adjuster simplifies the task of setting the fork pre-load or front height. The racer friendly SFF Type 2 also facilitates other maintenance chores like adjusting damping and changing springs.


The rear shock features dual compression adjustability, allowing high-speed and low-speed damping to be tuned separately. A self-lubricating anodised coating on the tank cylinder helps prevent wear abrasion, and reduces friction for smoother suspension action.

Revised valve settings contribute to improved ride feel and increased rear-end feedback.

Rear  shock spring 52 N/mm and the fine tuned damping settings offering greater composure when braking and accelerating.

Uni-Trak rear suspension system mounts the suspension arm below the swingarm, allowing a longer rear suspension stroke. The longer stroke in turn allows more precise rear suspension tuning. Extensive rider testing was conducted to determine the ideal linkage ratios and rear shock absorber damping settings to achieve maximum rear wheel traction.


For 2019, the ultra slim frame is one of the many components contributing to the KX250’s trim form. The light weighing 2019 KX250 model is quick both in the straights and through the corners. Suspension settings for the high-spec SFF Type 2 front fork and Uni-Trak rear shock settings were determined to deliver great stability over braking bumps and through corners. A slim, flat rider interface further enhances the adjustable racer-friendly ergonomics, helping racers to rider even faster.


Large oversized 270mm front disc contributes to race winning braking power and control.

The radical design front and rear petal discs offer strong braking performance, excellent competitive edge with high quality factory looks.


High-performance piston, featuring the same design used on our factory racers, contributes to strong performance at all rpm. A short skirt, reinforced external ribs and the use of a bridged-box bottom, featuring internal bracing, contributes to a light, strong piston design. Already the lightest piston in its class, the pistons design and strength optimisation help lower reciprocating mass and contribute to the engine’s strong performance. Piston pin is offset 0.25 mm, complementing the offset cylinder and help reduce mechanical losses. Strength optimisation results in a light piston pin design. Coating and striation on the piston outer surface ensure good wear resistance and oil retention for minimal sliding friction. The molybdenum coating also helps reduce mechanical loss.


Adjusting engine settings to suit conditions has never been easier than with the KX’s FI couplers. Plug-and-play style system is quick, easy and stress-free. Instead of a single engine map, the ECU features three (four, counting the Launch Control Mode map). Initial settings for the three maps are: Standard (green), Hard (conditions)(black) and Soft (conditions)(white). Using provided FI couplers, riders are able to easily switch between the three maps to suit riding conditions. Plugging in each of the 4-pin couplers activates the corresponding engine map. (Plug is conveniently located on the right side of the head pipe for easy access without having to remove any parts.)

Each of the three maps can be reprogrammed using the optional KX FI Calibration Kit.


The updated KX FI Calibration Kit features the handheld KX FI Calibration Controller, which enables expert riders to adjust engine characteristics (by rewriting actual data maps) to suit their preference.  This simple tool can be used without a PC, simply by plugging into the engine’s ECU.

The KX FI Calibration Controller is handheld tool with a built in colour LCD screen.  It comes with transfer and diagnostic cables, SD memory card, user manual and a carrying case.

Ask you Authorised Kawasaki Dealer for more information on this option.


The KX250 features a launch control system similar to that on our factory racers. With the simple press of a button, riders can activate a separate engine map designed to ensure efficient race starts in slippery conditions. The Launch Control Mode map retards ignition timing, allowing tyres to gain grip in low traction situations.

Launch Control Mode has the greatest effect within the first few seconds of releasing the clutch off the start. This is the most crucial time for the rider to get ahead of their rivals and line up the first corner.


To activate the Launch Control Mode riders depress the launch control button (for 2 seconds) located at the left handle. when activated the light next to the button will flash quickly to let the rider know it is on. Launch Control Mode works in 1st and 2nd gear.  Once the rider shifts into 3rd gear, the system is automatically disengaged, switching back to the normal engine mapping.


43 mm throttle body is both compact and light. The main injector is now mounted at 30° in the throttle body  and the FI settings have been optimised for the updated engine settings.

Designed specifically for motocrossers, the fuel injection system incorporates a small lightweight ECU and operates without a battery to further eliminate unnecessary weight.  And of course, fuel injection eliminates the need to adjust engine settings to suit track and climate conditions

The  KX250 fuel pump, located in the fuel tank, is a lightweight aluminium construction. The fuel pump’s high 343kPa pressure matches the high performance injector.


A choice of four positions allows riders to tailor their riding position. Factory-style Renthal handlebar and pad come standard.

Upper triple clamp with two sets of handle mount slots and reversible handle mounts offers riders a choice of four handle positions to choose from: 25 mm FWD, 15 mm FWD, STD and 10 mm BK.


Tuned to best suit race-experienced riders, the 249 cm3 liquid-cooled, 4-stroke single’s wide power-band focuses on high-rpm performance and extends way into the over-rev.  Highly acclaimed for its high output and smooth power delivery, the 2019 model KX250 backs up its dual-injected power and race-inspired tuning with the short downdraft-style intake duct, a large diameter and carefully tuned exhaust header pipe, matched to the optimised intake camshafts timing and the advanced dual injection EFI system results in excellent power/torque feeling make it easier to ride fast and enabling fast lap times.  Bottom-end to mid-range: The strong power/torque translates to smooth power engagement, making it easier to use the power band and requiring less attention to be spent on clutch work. Top-end: Thanks to the smooth power engagement, the high-rpm range is easy to use.


The use of the world’s first dual injectors for a production motocrosser is a key component of the KX250’s highly acclaimed fuel-injected performance. Tuned for high performance, its high-revving character is complemented by superb response. The short downdraft-style intake duct enhances the power and torque across the mid-top-end engine speed range.


The downstream injector is used to ensure smooth instant response while the upstream injector is chanrged with providing power. As RPM and throttle postion increase, primary operation switches from the downstream injector to the upstream injector.

Both fuel injection are fine atomising injectors with 4 holes, dispersing spray particles with a droplet size of 120 µm from the upstream injector and 75 µm fro the downstream injector. The downstream injector’s finer droplet size and wider spray angle contribute to stronger low-mid range power feeling, improved response and quicker acceleration.


Riders can choose from two positions on the footpegs to suit their body size and personal preferences.

The adjustable brackets enable riders to lower the footpeg position 5mm.  In the lower position, centre of gravity is lowered as is the rider’s point of view, adding to both the physical and psychological stability.


Matching the KX250’s light weight, the KX450-inspired minimalist bodywork makes the bike look compact. Its shroud, fender and number plate designs ensure it is the sharpest looking bike in the paddock.  Factory-style graphics further reflect the KX250’s highly tuned performance, while the in-mould graphics give the design high durability. Green highlights on the suspension adjusters and engine oil cap and generator cover plugs contribute to a distinctive Kawasaki look.

  • Kawasaki’s in-mould graphics used on the shrouds result in an ultra-smooth surface and ensure the racy graphics are not easily damaged.
  • Sharp and aggressive design of the front fender adds to the racy appearance. The rear fender’s sharp design contributes to the overall design.
  • Rims are coated in black alumite1–just like our factory racers.
  • Fork and rear shock adjusters have a green alumite1 finish like our U.S. factory racers.
  • SFF Type 2 forks are coated with a titanium hard coating for reduced friction and high durability.
  • Embossed Kawasaki logo on the clutch cover made to appear as the contact from your riding boots wears off the paint.
  • Green finish on the oil cap and the two plugs on the generator cover further contribute to factory looks.
  • Embossed design on the clutch cover designed to gradually appear as contact from riding boots wears off the paint.
  • Engine covers are finished in silver paint, further reinforcing the KX250’s factory image.

1 Alumite: an anodic oxidation finishing treatment for aluminium resulting in a coloured, corrosion/scratch-resistant film coating.

Model KX250 (KX252AKF)
Engine Type 4-stroke, liquid cooled, single cylinder
Displacement 249 cm³
Bore X Stroke 77.0 x 53.6 mm
Compression Ratio 13.4:1
Valve System DOHC, 4 valves
Fuel System Fuel injection: ø43 mm x 1 with dual injectors
Ignition Digital DC-CDI
Starting Primary Kick
Transmission 5-speed, return
Clutch Wet multi-disc, manual
Type Perimeter, aluminium
Wheel Travel Front 310 mm
Wheel Travel Back 310 mm
Front 80/100-21 (51M)
Rear 100/90-19 (57M)
Front ø48 mm inverted telescopic Separate Function front Fork (SFF) Type 2, 22-way compression damping, 20-way rebound damping and 40-way spring preload adustability
Rear Uni-Trak with adjustable dual-range (2 turns high speed / 19-way low-speed) compression damping, adjustable 22-way rebound damping and fully adjustable spring preload
Front Single semi-floating 270 mm semi-floating petal disc with dual piston caliper.
Rear Single 240 mm petal disc with single piston caliper.
L x W x H 2,172 x 825 x 1,270 mm
Wheelbase 1,478 mm
Ground Clearance 320 mm
Seat Height 945 mm
Curb Mass 104.7 kg (includes full fuel tank, all fluids at optimum levels)
Fuel Capacity 6.3 litres
Colour/s Lime Green
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