Technology PrintOverview The 2011 Kawasaki KX 450F base package provides an excellent platform for experienced racers to win races in the top classes. Design of the highly rigid aluminum frame, suspension components and settings focused on ensuring control is maintained during high-speed riding especially in straight lines to enable race-experienced riders to ride full out. And to deliver holeshot-winning performance a key factor that can mean the difference between running up front and winning, or getting stuck mid-pack chassis geometry and the hard-hitting 4-stroke engine’s wide powerband were designed to maximise rear wheel traction. The combination is a proven race-winner, with Kawasaki racers regular podium finishers.
To keep the Lime Green racers out in front, Kawasaki engineers made a number performance-enhancing updates to both engine and chassis in 2011 Kawasaki KX 450F. 449 cc liquid-cooled, 4-stroke Single with battery-less fuel injection Already featuring race-inspired tuning and parts like the high-performance piston with bridged-box bottom (a mass-production first when introduced on the 2010 KX450F), the 2011 engine receives further fine-tuning for increased low-end response, improved shift feel and other changes to meet stricter noise regulations.
Works-base bridged-box bottom piston (unique Kawasaki feature used for the first time on a mass-production motocrosser on the 10MY KX450F) is just one of many features inspired by our factory racers.
Progressive throttle link
Lightweight 43 mm throttle body uses two shafts joined by a progressive link to give sharp response and excellent power feeling.
NEW Setting-adjustable motocross ECU
Lightweight ECU was designed specifically to withstand the rigors of motocross racing. Revisions to software and hardware offer improved response at low-mid rpm and improved combustion. The KX FI Calibration Kit contains KX Racing software, an ECU controller, mounting brackets and damper, harness and USB cable. In addition to the kit, a PC and 12 V battery are all that is required.
NEW Reduced noise
Changes to silencer internals ensure that stricter noise regulations are met.
NEW Improved shift feeling
Shift mechanism revisions result in a firmer shift feel.
Dual-weight centrifugal decompression system offers reliable starting.
All-aluminum perimeter frame
Slim aluminum perimeter frame is a lightweight construction composed of forged, extruded and cast parts.
NEW Lighter-handling chassis
Increased chassis flex, revised rigidity balance and new front axle collars result in lighter turning, increased rear wheel traction, a more planted feel from the front wheel and enhanced cornering accuracy.
NEW Uni-Trak rear suspension
Linkage mounts below the swingarm for more precise suspension tuning.
NEW Kayaba AOS fork with DLC coating and Kashima Coat
Diamond-Like Carbon coating reduces sliding friction for improved fork action, especially during cornering. Kashima Coat and high-precision machining further reduce friction. For ’11, revised settings offer improved action and increased absorption performance.
NEW Rear shock absorber
Dual compression adjustability offers a wide range of tuning options. Kashima Coat on the tank cylinder improves action. For ’11, revised settings offer improved action and increased absorption performance.
A factory-style Renthal (standard-type) aluminum handlebar is standard equipment.
Slim rider interface
Bodywork components and seat designed to offer a slim, natural riding position making it easier for racers to go fast.
Revised pattern for the seat sides offers more grip.
Petal brake discs
The KX450F features petal brake discs front and rear.
NEW Factory styling
Factory-style graphics, black alumite1 rims , Fork and rear shock adjusters have a blue alumite1 finish like our US factory racers.
Hard-Hitting Fuel-Injected Power
Fuel-injected 449 cc liquid-cooled, 4-stroke Single delivers hard-hitting power from low- through high-rpm. The broad powerband and responsive throttle offer a broad spread of torquey response that enables racers to get on the gas and go even from down low. In addition to the inherent benefits, fuel injection contributes to the KX450F’s lag-free acceleration, especially after landing jumps. Already featuring race-inspired tuning and parts like the high-performance piston with bridged-box bottom (a mass-production first when introduced on the 2010 KX450F), the 2011 engine receives further fine-tuning for increased low-end response, improved shift feel and other changes to meet stricter noise regulations.
Factory-racer engine tuning
- High-performance piston, featuring the same design used on our factory racers, contributes to improved performance at all rpm. A short skirt, reinforced external ribs and the industry’s only mass-production use of a bridged-box bottom, featuring fully flush internal bracing, result in a lighter, stronger piston.
- Wedge-shaped crank web increases offsetting moment for high crankshaft balance factor. At close to 60%, the balance factor of the ’11 KX450F is on par with Chad Reed and Ryan Villopoto’s factory racers. The high balance factor contributes to reduced engine vibration, smoother power delivery and increased performance – especially at low rpm, where response is noticeably snappier.
- In addition to generating the electrical output necessary to ensure easy starting, the large-diameter ACG also contributes to engine feeling at partial throttle.
NEW - Changes to the ECU programme and settings and revisions to the primary ignition circuit result in improved low-rpm response. Additionally, these changes lengthen spark duration for improved combustion.
NEW - On North American models, revised internal construction results in a quieter silencer that clears stricter 94 dB noise regulations.
Improved shift feeling
NEW - Changes to the shift mechanism result in a firmer feeling when gears engage. The roller at the end of the position lever used to turn the shift cam ratchet has a larger diameter (16 mm >> 18 mm). Spring rate was increased 40% accordingly.
Battery-less fuel injection system
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.
- Ensuring quick starting without a battery was a prime directive when developing the KX450F’s fuel injection system. Using only electricity generated by the kick starter, the engine can be started with only three rotations of the crankshaft. The system delivers electricity in the following order: 1) ECU, 2) fuel pump, 3) injector. With a warm engine, starting can be accomplished in a single kick.
- The compact, lightweight ECU, located just in front of the steering head (behind the number plate), was designed specifically for motocross use. To help cope with the shocks and vibrations of motocross riding, the fuel pump relay is built in to the ECU.
- The 43 mm throttle body makes use of a progressive throttle link to deliver airflow in much the same way as would a FCR carburettor. Using two linked shafts, the throttle body opens more quickly after the 3/8 open position, delivering sharp response and excellent power feeling.
- Ultra-fine atomising injector with 12 holes sprays particles with a droplet size of 60µm for smooth power deliver and improved engine at partial throttle.
- The injector was set at 45°, the optimum angle for improved mid-range power.
NEW - Lightweight flat-bottom aluminum fuel pump is located in the plastic fuel tank. For ’11, the fuel pump mounting angle was rotated 55° to offer increased reliability.
- To ensure a stable fuel supply during vigorous motocross riding the fuel pump features a rubber fuel filter cover that wraps around the inlet port and acts as a fuel trap. A fuel return hose from the pressure regulator ensures there is always fuel in the fuel trap.
Factory KX FI Calibration Kit (optional part # 99999-0289 )
The KX FI Calibration Kit is the same kit used by Kawasaki’s works teams in Europe and the U.S. The kit enables expert riders to adjust engine characteristics (by rewriting actual data maps) to suit their preference, record riding data, and analyze their riding data to further fine-tune their settings.
- The KX FI Calibration Kit contains KX Racing software, an ECU controller, mounting brackets and damper, harness and USB cable. In addition to the kit, a PC and 12 V battery are all that is required.
- While the kit is designed to satisfy racers and expert riders, it is simple and hassle-free to use:
- the ECU controller mounts behind the number plate for easy access
- accessing the ECU is accomplished simply by connecting to a PC via the ECU controller using a USB cable (no additional switches are necessary)
- setting adjustments can be prepared in advance on a PC, or done when connected to the ECU
- the kit’s user-interface is simple to understand and easy to use
- The KX FI Calibration Kit contains seven preset settings that can be quickly and easily used to adjust the ECU to suit track conditions. The provided settings are shown below.
Richer fuel setting fuelling 5% richer than stock
Leaner fuel setting fuelling 5% leaner than stock
Advanced ignition setting ignition advanced 3° from stock
Retarded ignition setting ignition retarded 3° from stock
Hard riding surface setting ignition retarded, fuelling richer
Soft riding surface setting ignition advanced, fuelling leaner
Beginner setting engine power suppressed: ignition
retarded, fuelling richer
- For more advanced setting optimisation, the ECU maps for volume of fuel injected (via the FI adjustment window) and ignition timing (via the IG adjustment window) can be adjusted for given throttle position and rpm.
- Base settings are shown as a flat graph. Settings can be increased or decreased from the base according to rider preference.
- Multiple display options are available. Click [3D Graph] or [2D Graph] of the [3D/2D] to select the 3 or 2-dimensional display. When you use the [3D Graph], select [Surface Display] or [Frame Display] of the [3D Graph Type] to select the display type.
- Both click-and-drag (using the graph window) and numerical editing (using the map sheet) are possible.
- When connected to the ECU, the KX FI Calibration Kit can be used to display the status of a running engine. Information can be displayed in numeric form using the Data Monitor , or in visual form using the various display options offered by the Data Meter .
- The KX FI Calibration Kit can also be used as a data logger, recording up to six hours of data depending on the number of parameters (engine rpm, angle of throttle opening, etc) being recorded. After riding, the riding data can be viewed using the [Analyze] window . Parameters to be recorded and displayed can be selected independently.
- The logged data can lined up with the course layout to check actual riding, enabling more efficient FI settings to be determined. It also enables before-and-after comparisons and comparisons between riders.
For more detailed information on use and functions of the FI Calibration Kit, please refer to the KX FI Calibration Kit Instruction Manual.
Other performance-enhancing 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 maximised for a greater part of the rev range.
- 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.
- Asymmetrical high-acceleration cams yield high intake efficiency.
- 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.
- Lightweight titanium valves (IN: 36 mm; EX: 31 mm) reduce reciprocating weight and offer high-rpm reliability.
- Aluminum valve spring retainers reduce reciprocating weight for reliable valve control at high-rpm.
- Double valve springs also help ensure stable valve operation and allow a short cylinder head height.
- 32 mm thick, 127.8 mm wide radiators with wide fin and tube pitch offer resistance to mud build-up while maintain cooling performance. The radiators are strong enough that the reinforcing brackets could be eliminated, resulting in lower overall weight.
- The screw-type adjuster on the cam chain tensioner is equipped with a pressure spring. Because the system automatically minimises the vibration caused by a loose cam chain, it greatly reduces the chance of a mishap during a race. (Non-automatic systems that are tuned incorrectly can actually adversely affect valve timing by putting too much pressure on the cam chain.)
- The combination of the smooth-shifting, close-ratio 5-speed transmission with the KX450F’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.
- In the event of a stalled engine during a race, getting it started again as soon as possible is a racer’s first priority, so the KX450F is equipped with an automatic compression release (ACR) system. The dual-weight centrifugal decompression system fitted to the exhaust cam eases starting in much the same way as a conventional lever-type system.
- 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.
Factory-Style Chassis Components and Tuning
The KX450F’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 tyre would drive the bike forward (instead of causing it to squat). For ’11 the chassis was fine-tuned, with revisions to frame and suspension components resulting in improved turning, greater rear wheel traction, more planted feel from the front wheel and enhanced cornering accuracy. The KX450F’s highly acclaimed high-speed stability remains unchanged.
While the frame remains essentially the same as that of the 10MY model, revised rigidity balance results in a frame with moderate lateral flex.
NEW - Frame’s side hangers (engine mounting brackets), previously aluminum, are now formed from steel, and are thinner (t8.0 mm >> t4.5 mm).
NEW - The resultant increased lateral chassis flex enables lighter turning.
NEW - The revised rigidity balance offers a number of benefits:
- increased rear wheel traction
- more planted feel from the front wheel
- enhanced cornering accuracy makes it easier for riders to follow the line they want
NEW - Larger-diameter front axle collars (25 mm >> 27.5 mm) with higher rigidity contribute to the more planted feel from the front wheel.
Superior rear wheel traction
- 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.
- Extensive rider testing was conducted to determine the ideal linkage ratios and rear shock absorber damping settings to achieve maximum rear wheel traction.
- Kayaba AOS (Air-Oil-Separate) fork keeps oil and air in separate chambers for stable damping performance during long motos. Low-friction fork seals contribute to smooth action.
NEW - Lighter fork internals save 50 g each (100 g total).
NEW - Revised fork damping settings complement the changes to the frame and front axle collars, offering improved action and increased absorption performance.
- A super-hard DLC coating (Diamond-Like Carbon) on the outer surface of the inner fork tubes reduces sliding friction (and stiction) and gives better action, contributing to the smoother ride. The coating is even effective when the fork is exposed to lateral forces that would usually hamper slide action, such as during cornering. The increased surface hardness also minimises 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 rear shock damping settings complement the changes to the frame and front axle collars, offering improved action and increased absorption performance.
- 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.
Factory-style and other race-oriented components
- The KX450F features petal brake discs front and rear. In addition to helping reduce unsprung weight, the wave shapes of the petal discs help clean the brake pads for more efficient 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.
- Rims are coated in black alumite1 – just like our factory racers.
NEW - Fork and rear shock adjusters have a blue alumite1 finish like our US factory racers.
- Factory-style graphics complement the KX450F’s highly tuned performance.
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.
- Formed using a double-injection moulding process, 2-tone shrouds contribute to the slim package.
- 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.
- Optimised exhaust pipe line also contributes to the racer-friendly ergonomics.
- The seat uses a slip-resistant top surface for good grip when seated and smooth sides for excellent rider mobility.
NEW - Revised pattern for the seat sides offer more grip than before.
- Seat urethane designed to keep the original shape longer.
- 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.
NEW - Changes to the piston profile result in reduced variance in piston clearance, contributing to improved exhaust emissions.
- Fast-idle knob on the throttle body allows riders to increase engine speed when first starting a cold engine.
- The crankshaft and connecting rod received a carburising and quenching treatment for additional rigidity.
- The camshaft lobes and tappet surfaces feature a soft-nitriding surface treatment for long wear and high-rpm reliability.
- A large flap inside the air cleaner case helps prevent the ingress of mud.
- The silencer uses long-fibre packing which is much more resistant to being blown out of the tail pipe than standard length packing. As a result, packing needs to be replaced half as often.
- The alloy swingarm uses a cast front section, tapered hydroformed spars and forged chain adjusters.
- Designed to accommodate the in-tank fuel pump, the plastic fuel tank is formed using a rotational moulding (or rotomoulding) process that reduces weight.
- Large synthetic skid plate offers great protection with minimum weight.
NEW - Front chain guide (chain slider) uses a thicker plastic lining, offering longer wear life.
- Optional engine parts include magneto rotors with different inertias (8.5, 9.5 kgfcm2; STD: 9.0 kgfcm2).
- Optional chassis parts include handlebar holder for a f28.6 mm bar (STD: f22.2 mm), aluminum and steel rear sprockets (48-52T; STD: 50T), solid petal brake rotors for wet races, and different springs for the front fork (4.6, 4.8 N/mm; STD: 4.7 N/mm) and rear shock (52, 56 N/mm, STD: 54 N/mm).
- An FI indicator lamp (Optional part# 23016-0049) warns of any problem with the FI system.
2011 Kawasaki KX 450F - USA Specifications
Engine: Liquid-cooled, four-stroke single with DOHC and four-valve cylinder head
Bore x stroke: 96.0 x 62.1mm
Compression ratio: 12.5: 1
Fuel System: 43mm Keihin throttle body
Ignition: Digital DC-CDI
Rake / trail: 26.7 degrees / 4.6 in.
Front suspension / wheel travel: Uni-Trak® linkage system and Kayaba shock with 50mm piston, 22-position low-speed and stepless high-speed compression damping, 33-position rebound dampening and fully adjustable spring preload / 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, 33-position rebound dampening and fully adjustable spring preload / 12.4 in.
Front tire size: 90/100-21
Rear tire size: 120/80-19
Front brakes: Single semi-floating 250mm petal disc with dual piston caliper
Rear brakes: 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: 13.2 in
Seat height: 37.8 in.
Curb weight: 249.9 lbs.
Fuel capacity: 1.9 gal.
Color Choices: Lime Green
2011 Kawasaki KX 450F - Canada Specifications
MSRP: $TBA CDN
Type Liquid-cooled, 4-stroke Single
Displacement 449 cc
Bore and Stroke 96.0 x 62.1 mm
Compression Ratio 12.5:1
Valve System DOHC, 4 valves
Fuel System Fuel Injection: ø 43 mm x 1 (Keihin)
Ignition Digital DC-CDI
Starting Primary Kick
Lubrication Forced lubrication, Semi-dry sump
Transmission 5-speed, return
Final Drive Chain
Primary Reduction Ratio 2.727 (60/22)
Gear Ratios: 1st 1.750 (28/16)
2nd 1.412 (24/17)
3rd 1.188 (19/16)
4th 1.000 (19/19)
5th 0.875 (21/24)
Final Reduction Ratio 3.846 (50/13)
Clutch Wet multi-disc, manual
Type Perimeter, Aluminum
Wheel Travel: Front 315 mm
Wheel Travel: Rear 315 mm
Tire: Front 90/100-21 57M
Tire: Rear 120/80-19 63M
Caster (Rake) 26.7°
Trail 116 mm
Steering Angle (Left/Right) 42°/42°
Front: Type 48 mm inverted AOS-type telescopic fork
Compression Damping 22-way
Rebound Damping 20-way
Rear: Type New Uni-Trak
Compression Damping 22-way (low-speed), 2-turns or more (high-speed)
Rebound Damping 22-way
Spring Preload Fully Adjustable
Front: Type Single semi-floating, 250 mm petal disc
Rear: Type Single 240 mm petal disc
Overall Length 2,185 mm (86 in.)
Overall Width 820 mm (32.3 in.)
Overall Height 1,280 mm (50.4 in.)
Wheelbase 1,480 mm (58.3 in.)
Ground Clearance 335 mm (13.2 in.)
Seat Height 960 mm (37.8 in.)
Curb Mass 113.4 kg (250 lbs.)
Fuel Capacity 7 litres (1.54 gal.)
Colours Lime Green
* The Manufacturer's Suggested Retail Price does not include freight, pre-delivery inspection or applicable taxes. The final price is at the discretion of the dealer. Prices and Specifications are subject to change without prior notice.
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.