2020 KX450



To maintain its edge in this fiercely competitive class, the 2020 KX450 benefits from an engine mounted in its leanest chassis to date, enabling it to turn even quicker lap times, and make it the most powerful machine in the paddock. Complementing its already high performance, with a number of features – including finger-follower valve actuation, electric start and a hydraulic clutch, – further elevate its race-winning potential. 

Designed with mid-level to expert riders in mind, the KX450 motorcycle has always been built with one goal in mind: to put riders on the top step of the podium. And for over 40 years KX brand motocrossers have been extremely successful at doing just that.


Powerful Engine

The engine design boasts awesome power while a flatters torque curve makes is easiler to get on the gas. Finger-follower valve actuation (a valve train designed by Kawasaki’s MotoGP & World Superbike engineers) enables larger diameter valves and more aggressive cams. Downdraft style intake and reduced friction loss (care of a plain bearings for the connecting rod big-end) further contribute to the power gains.

Hydraulic Clutch

Kawasaki’s hydraulic clutch on a motocrosser offers more direct feel and lighter lever action. Less play as the clutch heats up during heavy use results in more consistent feeling.

Light Weight & Light, Nimble Handling

Complementing the powerful engine, light, nimble handling contributes to the KX450’s quick lap times. With electric start and the coil-spring fork  The KX450’s lean chassis, and a highly-competitive, low overall weight of only 110.0 kg.


Front/Rear Traction

Increased front and rear traction ensure the bike can put power to the ground and get around corners quickly. A large diameter front axle (a hint from our racing teams) helps at the front, while rear suspension layout and linkage ratios benefit the rear.

Electric Start

Being able to restart an engine quickly during a race can mean the difference between keeping your lead, or having to fight your way back through the pack. Kawasaki’s electric start on a motocrosser makes restarting the engine as easy as pushing a button. Starting is electric only, via a button located on the right grip.

Large-Diameter Coil-Spring Fork

Handling suspension duties up front is a high performance 49 mm inverted coil-spring fork. The large diameter inner tubes (the same size as on our factory racers) enables the use of large damping pistons, delivering smooth action and firm damping.  A super-hard titanium coating on the outer surface of the fork inner tubes helps prevent wear abrasion. The increased surface hardness of the dark navy blue coating also helps to prevent scratches and damage to the tubes.

Kashima Coat Forks

Kashima Coat creates a hard, low-friction surface on the outer tubes. The hard coating helps prevent wear abrasion on the inside of the tubes, ensuring the sliding surfaces remain smooth for a long time, while the outside is protected against corrosion. The lubricating material in the coating contributes to smoother suspension action (especially at the initial part of the stroke) and a better ride feel.

Lightweight, Aluminium Perimeter Frame

Slim aluminium perimeter frame is a lightweight construction composed of forged, and extruded cast parts. An evolution of  design, the frame offers a better overall rigidity balance. Engine is used as a stressed member. The swingarm is matched to the frame to improve rear traction. 

Downdraft Intake & Large Throttle

Downdraft-style intake routing allows an even straighter approach for intake air. The intake air’s approach angle into the cylinder is 20°, improving cylinder filling efficiency and contributing to increased engine power.  Large-diameter (ø43 mm >> ø44 mm) – it turns in the opposite direction to open – flows a greater volume of air, providing increased performance – especially at high rpm and over-run – and driveability.

 Advanced Engine Design

The finger-follower valve actuation reduces the valve train mass (IN is 4.2% lighter; EX is 7.9% lighter) compared to a tappet-style valve actuation (even taking into account larger-diameter valves). DLC (Diamond-Like Carbon) coating on the finger followers helps protect against wear. Complementing more aggressive cams, large-diameter intake 40 mm diameter and exhaust valves 33 mm diameter with increased lift flow more air, contributing to the increased power. The camshafts benefit from a thin and highly durable gas-nitriding treatment for long wear and high-rpm reliability. Valves are formed from lightweight titanium, reducing reciprocating weight and offering high-rpm reliability. SCr (chromium steel) valve spring retainers contribute to increased reliability at high-rpm.

High Performance Engine

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. This design and strength optimisation results in a light piston (259.8 g >> 243 g), reducing reciprocating weight and contributing to the engine’s performance. With needle bearings to the connecting rod big-end, reduces mechanical loss, contributing to overall performance.

Exhaust System

With a long header pipe (590 mm >> 695 mm) contributes to increased low end power.

Uni-Trak Rear Suspension

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

Factory Styling

Complementing the KX450’s sleek bodywork, factory-style graphics ensure it is the sharpest looking bike in the paddock and further reflect the KX450’s highly tuned performance. Green highlights on the suspension adjusters and engine oil cap and generator cover plugs contribute to a distinctive Kawasaki look. In-mould graphics used on the shrouds result in an ultra-smooth surface and ensure the racy graphics are not easily damaged. Aggressive design of the front fender adds to the racy looks. Rims are coated in black alumite – just like our factory racers. Fork and rear shock adjusters have a high-quality green alumite finish on the oil cap and the two plugs on the generator cover further contribute to racy looks.


Front Brake

Petal disc brakes are among the KX450’s numerous factory-style components. The stylish discs contribute to both sporty looks and a high-quality appearance. Oversized semi-floating 270 mm diameter front disc contributes to strong front brake force, as well as superb controllability. The front brake master cylinder offers better initial control, while contributing to overall braking performance.

Larger Rear Brake

A large-diameter rear disc 250 mm diameter matches the large front disc and contributes to stronger stopping power.

Lightweight Lithium Battery

Lightweight, compact Li-ion Battery helps keep the weight gain to a minimum.


Swingarm rigidity matched to the frame, contributes to increased rear traction. 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) are chosen so that the rear tyre drives the bike forward (instead of causing it to squat).

Adjustable Footpegs

Adjustable footpeg brackets enable riders to lower their footpeg position, 5 mm. In the lower position, centre of gravity is lowered as is the rider’s point of view. The wide footpeg design, offers excellent grip, superb feel, and making it easier to weight the pegs.


Adjustable Ergonomics

A choice of four handlebar positions and two footpeg positions allows riders to tailor their riding position to suit body size and preference. 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 forward, 15 mm forward, STD and 10 mm back.


Narrow and Flat Seat

Bodywork designed to facilitate rider movement features long, smooth surfaces that make it easy to slide back and forth. Seams between the shrouds, seat and side covers are very flush, which facilitates control as well as moving around on the bike. the flatter design of the fuel tank allows an even flatter progression from the seat to the tank. The flat design gives the rider greater freedom of movement when changing riding position, and allows the rider to sit further forward. The seat uses a slip-resistant top surface for good grip when seated and smooth sides for excellent rider mobility. Seat urethane helps maintain the original shape longer.

Slim Shrouds

Slim shrouds are positioned close to the frame. Being slim where they come in contact with the rider’s legs, the single piece shrouds are easier to hold on to. 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. Smooth engine covers are also designed to not impede rider movement.

Launch Control Mode: The Holeshot Advantage

The KX450 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. Even for top-level riders, controlling the massive power of a 450cc-class motocrosser off the start requires a high degree of throttle control and clutch finesse. By slightly reducing this power, Launch Control Mode helps riders maximise traction, increasing the chance of getting a good start. Launch Control Mode works in 1st and 2nd gear (and Neutral). Once the rider shifts into 3rd gear, the system is automatically disengaged, switching back to the normal engine map.

Setting-Adjustable Motocross ECU

Adjusting engine settings to suit conditions has never been easier than with the KX’s DFI 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, Hard and Soft (conditions). Using provided DFI couplers, riders are able to easily switch between the three maps to suit riding conditions. (Plug is conveniently located on the right side of the head pipe for easy access without having to remove any parts.) Maps can now be changed while the engine is running. ECU settings include programming that enhances traction by retarding ignition when the rear wheel speed increases too quickly (i.e. from sudden, excess wheel spin).

KX FI Calibration Controller (Accessory)

KX FI Calibration Kit features the KX FI Calibration Controller, with is built in colour LCD screen, transfer and diagnostic cable SD card, user manual and carry case. Enables riders to make changes to engine maps by plugging into the ECU without needing a PC or battery. Comes equipped with seven preset map settings.

Wheels and Tyres

Based on feedback from our factory race teams, the KX450 features a large-diameter front axle shaft 22 mm diameter, which contributes to greater front-end traction. Dunlop MX3S tyres contribute to increased front and rear traction.

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ModelKX450  (KX450JLF)
Engine Type4-stroke, liquid cooled, single cylinder
Displacement449 cm³
Bore x Stroke96.0 x 62.1 mm
Compression Ratio12.8:1
Valve SystemDOHC, 4 valves 
Fuel SystemFuel injection: ø43 mm x 1
IgnitionDigital DC-CDI
StartingElectric starting
Transmission5-speed, return
ClutchWet multi-disc with Brembo hydrualic operation
FramePerimeter, aluminium
Wheel travel - front305 mm
Wheel travel - rear305 mm
Tyre Size-front80/100-21 (51M)
Tyre Size-rear120/80-19 (63M)
Suspension - front49 mm inverted telescopic spring fork with adjustable compression and rebound damping
Suspension - rearNew Uni-Trak with adjustable dual-range (high/low-speed) compression damping, adjustable rebound damping and adjustable preload
Brakes - frontSingle 270 mm semi-floating petal disc with dual piston caliper
Brakes - rearSingle 240 mm petal disc with single piston caliper
L x W x H2,195 x 820 x 1,280 mm
Wheelbase1,495 mm
Ground Clearance335 mm
Seat height950 mm
Fuel capacity6.3 litres
Curb Mass108.8 kg (includes full fuel tank, all fluids at optimum levels)
ColourLime Green
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