2019 Kawasaki KX450

Updated engine, frame, suspension, brakes & bodywork

New electric start & hydraulic clutch

Kawasaki have revealed their 2019-model KX450, featuring a huge raft of updates and improvements, and designed to take the machine to the next level in the highly competitive class, focusing on racing and aimed at those from the mid-level riding right through to experts.

Kawasaki have boosted engine output with the updated engine now mounted in a new frame complete with new swingarm.

Several firsts for a Kawasaki Motocrosser also debut for MY19 with electric start, a hydraulic clutch and finger-follower valve actuation.

Updated Engine

The new engine boasts an increase in peak power of approximately 2.5kW (3.4PS), while a flatter torque curve makes it easier to get on the gas. Finger-follower valve actuation enables larger-diameter valves and more aggressive cams.

Downdraft-style intake and reduced friction loss (care of new plain bearings for the connecting rod big-end) further contribute to the power gains.

• NEW – Valve train designed by Kawasaki’s MotoGP & World Superbike engineers uses finger-follower valve actuation, enabling larger-diameter valves and more aggressive cam
• NEW – The change to 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.
• NEW – DLC (Diamond-Like Carbon) coating on the finger followers helps protect against wear.
• NEW – Complementing more aggressive cams, larger-diameter intake (φ36 mm >> φ40 mm) and exhaust valves (φ31 mm >> φ33 mm) with increased lift (IN: 9.8 mm >> 11.0 mm; EX: 9.0 mm >> 9.5 mm) flow more air, contributing to the increased power.

• NEW – The camshafts benefit from a thin and highly durable gas soft-nitriding treatment for long wear and high-rpm reliability.
• Valves are formed from lightweight titanium, reducing reciprocating weight and offering high-rpm reliability.
• NEW – SCr (chromium steel) valve spring retainers contribute to increased reliability at high-rpm.
• NEW – 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. Revised design and strength optimisation results in an even lighter piston (259.8 g >> 243 g), further reducing reciprocating weight and contributing to the engine’s increased performance.
• NEW – A change from needle bearings to plain bearings for the connecting rod big-end reduces mechanical loss, contributing to overall performance.
• The engine is almost upright (forward lean angle is 3°) to help place the bike’s centre of gravity in the ideal position for maximum traction.
• Cylinder is offset (8.5 mm forward), reducing friction and enabling more efficient power generation.
• 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).
• NEW – Thinner air cleaner element restricts airflow less, contributing to increased performance at all rpm.

• NEW – Downdraft-style intake routing allows an even straighter approach for intake air. The intake air’s approach angle into the cylinder increases from 10º to 20º, improving cylinder-filling efficiency and contributing to increased engine power.
• NEW – Larger-diameter (φ43 mm >> φ44 mm) throttle with reversed orientation – it turns in the opposite direction to open – flows a greater volume of air, contributing to increased performance – especially high rpm and over-run – and driveability.
• NEW – Fine-atomising injector with 12 holes sprays particles with a droplet size of 75 μm (previously 60 μm) and flows over 20% more fuel (391.7cc >> 478.3cc), contributing to the engine’s increased power. The fine droplet size contributes to smooth power delivery and superb engine response at partial throttle.
• Lightweight flat-bottom aluminium fuel pump is located in the plastic fuel tank.
  NEW – Revised fuel pump design is more compact, enabling a flatter design for the top of the tank. (See also Ergonomics below)
• During the cylinder head casting process, the cores for the intake ports were given a special coating to make the intake ports smoother. The extremely smooth surfaces that result increase intake efficiency at all rpm.
• NEW – Longer header pipe (590mm >> 695mm) contributes to increased low-end power.

• NEW – Kawasaki’s first 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.
• The combination of the smooth-shifting, close-ratio 5-speed transmission with the KX450’s low-rpm engine performance offers the rider the option to shift to a higher gear when traversing rough sections. This reduces the effect of sudden (unwanted) throttle input, allowing focus to be given to racing rather than careful throttle control.
• NEW – Revisions to the change drum and shift fork save 15g in weight.

New 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 first electric start on a motocrosser makes restarting the engine as easy as pushing a button.

• NEW – Starting is electric only, via a button located at the right grip.
• NEW – Lightweight, compact Li-ion battery helps keep weight gain to a minimum.
• NEW – KX250-style automatic centrifugal decompression system fitted to the exhaust cam lifts one exhaust valve to facilitate starting. The system’s simple construction ensures light weight and high reliability.

Launch Control Mode

Factory-style launch control system increases the chance of getting a good start by helping riders maximise traction when starting on a slippery surface.

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. (The Launch Control Mode map retards ignition timing, allowing tyres to gain grip in low-traction situations, and allowing riders to focus on their lines.)

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 riders to get ahead of their rivals so they are better positioned going into the first corner.

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.

To activate Launch Control Mode riders depress the launch control button (for two seconds or more), located at the left handle.

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. The system is designed to the same specifications as that of our AMA factory racers.

DFI Setting Data Selection

Using the provided DFI couplers, riders can quickly and easily access their choice of three maps (standard, hard, soft) provided in the 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 (conditions) and Soft (conditions). Using provided DFI 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.)

A new feature is maps can now be changed while the engine is running. Each of the three maps can be reprogrammed using the optional KX FI Calibration Kit. (Please see below.)

KX FI Calibration Kit (Accessory)

The 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.  Comes equipped with seven preset map settings.

The KX FI Calibration Controller is a 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. While the controller is designed to satisfy racers and expert riders, it is simple and hassle-free to use.

Accessing the ECU is accomplished simply by connecting the controller using the provided cables (no PC or battery necessary). The kit’s user-interface is simple to understand and easy to use. Maps can be stored on a PC: data transfer between the controller and a PC can be done via SD card

The KX FI Calibration Controller contains seven preset map settings that can be quickly and easily used to adjust the ECU to suit track conditions. The provided settings are shown below.

Setting Description

• Richer fuel setting fuelling 5% richer than stock
• Leaner fuel setting fuelling 5% leaner than stock
• Advanced ignition setting ignition advanced 3o from stock
• Retarded ignition setting ignition retarded 3o from stock
• Hard riding surface setting ignition retarded, fuelling richer
• Soft riding surface setting ignition advanced, fuelling leaner
• Low-power setting engine power suppressed: ignition retarded, fuelling richer

For more advanced setting optimisation, the ECU maps for volume of fuel injected and ignition timing can be adjusted for given throttle position and rpm. When connected to the ECU, the KX FI Calibration Controller can be used to display the status of a running engine. KX FI Calibration Controller can be used with older fuel-injected KX models (2015 and earlier).

For more detailed information on use and functions of the KX FI Calibration Controller, refer to the KX FI Calibration Controller User Manual.

New Lightweight Aluminium Perimeter Frame

An evolution of the current design, the new frame features revised rigidity and includes the engine as a stressed member. A new swingarm also contributes to the revised rigidity balance and increased rear traction.

The slim aluminium perimeter frame is a lightweight construction composed of forged, extruded and cast parts. An evolution of the current design, the new frame offers a better overall rigidity balance. The engine is used as a stressed member, contributing to the frame’s rigidity balance.

A new steering head area with optimised rigidity, main frame rails with revised cross-sections, and a revised line for the swingarm brackets contribute to the overall rigidity balance. Wider lower frame rails also contribute to overall rigidity balance.

Swingarm rigidity was also revised to match the frame, and 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) were chosen so that the rear tyre would drive the bike forward (instead of causing it to squat).

New Coil-Spring Fork & Shock

Handling suspension duties up front is a new high-performance φ49 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.

New large-diameter inner tubes (the same size as on our factory racers) enable 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. 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 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 coat contributes to smoother suspension action (especially at the initial part of the stroke) and a better ride feel.

The New 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. Revised linkage ratios also contribute to increased rear wheel traction.

Shifting the shock 5mm to the right allows room for the new downdraft-style engine intake. Revised rear shock layout also contributes 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.

New brakes

A larger-diameter φ250 mm rear disc complements the oversized φ270 mm front disc, delivering stronger stopping power. A new front brake master cylinder offers better initial control, while contributing to overall braking performance.

Petal disc brakes are among the KX450’s numerous factory-style components. The discs contribute to both sporty looks and a high-quality appearance. Oversized semi-floating φ270 mm front disc contributes to strong front brake force, as well as superb control.

A revised front brake master cylinder offers better initial control, while contributing to overall braking performance.

A larger-diameter rear disc (φ240 mm >> φ250 mm) matches the large front disc and contributes to stronger stopping power. The revised rear brake master cylinder and hose are lighter.

New bodywork

All-new bodywork (except the front fender and number plate) was designed to facilitate rider movement. Long, smooth surfaces make it easy to slide back and forth. The tank is lower and flatter, making it easier to sit farther forward. Slimmer shrouds are easier to hold on to. Even the engine covers are smooth so that they do not impede rider movement.

Complementing the KX450’s sleek new bodywork, factory-style graphics ensure it is the sharpest looking bike in the paddock and further reflect the KX450’s 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. The aggressive design of the front fender adds to the racy looks.

Rims are coated in black alumite – just like the factory racers’. Fork and rear shock adjusters have a high-quality green alumite finish. Green finish on the oil cap and the two plugs on the generator cover further contribute to racy looks.

Adjustment & Ergonomics

A smoother, flatter rider interface further improves the adjustable racer-friendly ergonomics, helping racers to ride even faster.  Factory-style Renthal (standard-type) aluminium handlebars are standard equipment.

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: 25mm forward, 15mm forward, STD and 10mm back.

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.

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.

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.

Revised footpeg design is 5mm wider (front-to-rear) and positioned 3mm rearward, offering grip, feel, and making it easier to weight the pegs. The new design is also lighter.

Weight Savings

Complementing the powerful engine, light nimble handling contributes to the KX450’s quick lap times. While the addition of electric start and the return to a coil-spring fork add weight, efforts were made to keep the weight gain to a minimum. The result is the KX450’s leanest chassis to date, and a competitive, low overall weight of only 110kg – a gain of only 1.3kg.

Savings from the engine group (including intake and exhaust systems) amount to approximately 0.93 kg; savings from chassis components total approximately 0.85 kg.

Some of the major contributing components include:

• ENGINE
  • Revised duct, air cleaner construction -390 g
  • Revised decompressor construction -200 g
  • Optimised crankshaft design, new connecting rod bearings -177 g
  • Aluminium silencer cap -60 g
  • Smaller camshaft bearings -40 g
  • Smaller fuel pump -34 g
  • Rubber cooling system fittings -30 g
• CHASSIS
  • New footpegs and aluminium brackets -260 g
  • Main frame -140 g
  • Change to aluminium brackets for electrical components -140 g
  • New brake components (F/R) -100 g
  • Hollow link bolts + aluminium collars -90 g
  • Aluminium engine hangers -70 g
  • Front engine mount (bolt >> stud) -50 g

Wheel & Tyre updates

Based on feedback from the factory race teams, the KX450 features a larger-diameter front axle shaft (20mm >> 22mm), which contributes to greater front-end traction, while Dunlop tyres contribute to increased front and rear traction.

Accessories

Optional chassis parts include handlebar holders for a 28.6 mm bar (STD: 22.2 mm), aluminium and steel rear sprockets (49-51T; STD: 50T), different springs for the rear shock (49, 51, 53, 55 N/mm; STD: 52 N/mm), plain shrouds (without graphics), and a skid plate.