2015 Kawasaki KX450F Preview | Upgraded Suspension & Engine

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2015 Kawasaki KX450F

There’s no doubting the Kawasaki KX450F’s performance on the national-racing stage. With Ryan Villopoto at the controls, Kawasaki’s KX450F won the last four AMA Supercross titles.

But Kawasaki wants to make things better. For 2015, the KX450F has been updated with many improvements for enhanced ridability, including new suspension, larger brakes, and some engine modifications.

In the suspension department, the 2015 Kawasaki KX450F was upgraded with a Showa SFF-Air TAC Fork with Triple Air Chamber, and a Uni-Trak rear suspension with Showa shock.

The front suspension setup – technology that arrives directly from Villopoto’s title-winning machine – separates the damping forces into the left fork tube, while the pneumatic spring is housed on the right tube for less friction, better movement and a lighter fork.

Each 2015 KX450F purchase also arrives with a high-pressure 300psi digital air pump to tune the forks.

For 2015, Kawasaki upgraded the brakes with a larger, 270mm “oversized” front disc, up front the 250mm disc offered in 2014. The front setup is combined with a 240mm rear rotor. All discs are petal shaped to shed off dirt, allowing for more powerful braking.

Kawasaki has also upgraded the engine with a revised bridged-box-bottom piston, and some updated ECU programming.

Due to the new piston, the 449cc engine, which features an industry-first Launch Control System, has a higher compression ratio of 12.8:1, up from 12.5:1 offered on the 2014 model. The piston design was also developed on Villopoto’s factory racer and provides a stronger mid-range hit as well as a stronger feeling at high RPM.

Kawasaki also revised the ECU programing to enhance traction by retarding the ignition when excess wheelspin is detected by a sudden surge in RPM. Like always, the ECU is full reprogrammable, and custom maps can be created using the optional accessory Kawasaki Racing Software Kit giving riders total power adjustability. This is the same tool used by Kawasaki factory and privateer teams in AMA and FIM racing.

The 2015 Kawasaki KX450F is available in one color – Lime Green – and is offered for a price of $8,699.

Following are the features and specs of the 2015 Kawasaki KX450F.

2015 Kawasaki KX450F Features:


• Launch Control helps to reduce wheelspin on slippery starting gates
• Showa SFF-Air TAC fork with triple air chamber uses air spring to reduce weight, compared to traditional metal-coil fork springs, providing effective tuning and bottoming resistance
• Includes a free digital Kawasaki Genuine Air Fork Pump for quick and easy tuning of fork spring pressure
• Engine is tuned for optimum power delivery all the way from basement revs through the upper RPM range, this results in impressive thrust that continues from corner-exit to the end of the straights
• Revised Bridged-Box-Bottom piston. Piston crown increases compression and boosts performance (12:8.1 from 12:5.1 on the 2014 model).
• Intake cam shape promotes strong low-RPM throttle response
• Larger 270mm “oversized” Braking-brand petal-shape front disc, 240mm petal-shape rear disc
• Front master cylinder features a knocker-style lever-to-piston interface for excellent feel and superbly consistent performance
• Pre-programmed ignition maps are interchangeable trackside, no PC required
• Adjustable 4-position handlebar and 2-position footpegs allow riders to fit the KX to match their personal preference
• Black anodized aluminum rims for a factory look

2015 Kawasaki KX450F Engine Overview

• 449cc, liquid-cooled, DOHC, four-stroke single with legendary Kawasaki power!
• Works-based Bridged-Box-Bottom piston has optimum rigidity for maximum high-rpm power and durability
• A forward lean angle of 3° puts the engine in the ideal position for maximum traction
• Highly balanced crankshaft, on par with Villopoto’s factory racer, creates minimal vibration and has a high inertial mass to help maximize rear wheel traction
• Compact cylinder head is only 100mm tall
• Double valve springs help ensure stable valve operation and also allow for a short cylinder head height
• Camshafts, lobes and tappet surfaces feature a soft-nitride treatment for long wear and high-rpm reliability
• Automatic cam chain adjuster is maintenance-free
• Crankshaft and connecting rod feature a special carburizing and quenching treatment to maximize rigidity, boosting long-term reliability without adding weight

2015 Kawasaki KX450F Digital Fuel Injection

• Digital Fuel Injection (DFI®) self-adjusts to atmospheric changes for easier starting, sharper throttle response and accessible power for jumping
• It is not necessary to re-tune or change any jets to suit climatic conditions like carbureted models
• Ultra-fine atomizing injector with 12 holes sprays particles with a droplet size of 60μ for smooth power delivery and engine response throughout the throttle range
• 43mm throttle body uses a progressive throttle linkage to deliver airflow in much the same way as an FCR carburetor
• Using two linked shafts, the throttle body opens more quickly after reaching the 3/8 open position
• Fast-idle knob on the throttle body allows riders to increase engine speed when starting a cold engine
• Fuel injector set at 45°, the optimum angle for mid-range power

2015 Kawasaki KX450F High-performance Multi-map ECU

• Revised ECU programming enhances traction by retarding ignition when excess wheelspin is detected by a sudden surge in RPM.
• Ignition timing boosts response when re-opening the throttle after deceleration (when landing jumps, etc.)
• ECU programming is easily selectable via interchangeable DFI coupler caps that provide three preprogrammed maps for standard, hard (terrain) and soft (terrain), without the need for a separate programmer or laptop
• The engine can be started with only three rotations of the crankshaft using the electricity generated by a single kick of the starter, no battery needed
• The system delivers electricity to the bike’s electronics in sequence: first the ECU, then the fuel pump, and finally the injector for quick, easy starting
• The compact, lightweight ECU, located on the front of the steering head behind the number plate, was designed specifically for motocross use. The fuel pump relay is integrated with the ECU to help cope with the shocks and vibrations of tough racing

2015 Kawasaki KX450F Launch Control Mode

• Factory-style launch control system is an industry first and increases the ability to get good starts by maximizing available traction
• Push-button activation of the Launch Control Mode retards ignition timing in first and second gears, giving the greatest effect within the first few seconds of releasing the clutch
• Launch Control can be activated in neutral, first or second gear
• Shifting into third gear automatically deactivates Launch Control Mode and returns the ignition to normal mapping

Easy Starting

• Strong output from the large ACG rotor provides enough electrical power for the battery-less FI system to enable true one-kick starting without using a battery
• Equipped with an automatic compression release (ACR) system for quick and easy starting. The dual-weight centrifugal decompression system is fitted to the exhaust cam
• Compression release features 1.0mm of valve lift, to minimize the required kicking power

2015 Kawasaki KX450F Bridged-Box Bottom Piston

• Piston crown shape tuned for excellent low to mid-range engine response
• Same design as used on our factory racers; offers optimum performance at all rpm
• Lighter and more durable than traditional piston designs
• Short piston skirt features low-friction coating to minimize mechanical losses
• Reinforced external ribs enhance strength and durability

2015 Kawasaki KX450F Showa SFF-Air TAC Front Fork

• Showa SFF-Air TAC fork with triple air chamber uses air as a spring. The reduced weight and inertia of the air spring improves smoothness and enhances the fork’s ability to follow terrain contours
• Air spring significantly reduces friction and cuts weight while also providing better bottoming resistance, less oil contamination, plus easier and more effective tuning compared to traditional springs
• Large diameter internal damping cartridges help provide consistent performance and bottoming resistance
• A removable spring pressure adjustment valve and free 0-300psi digital Kawasaki Genuine Air Fork Pump are included for quick and easy tuning of fork spring pressure
• Hard titanium coating on the outer surface of the inner fork tubes offers minimum stiction when the fork is exposed to lateral forces that would usually hamper slide action. The result is improved fork response, especially during cornering
• Friction-reducing Kashima Coat on the inside of the fork’s outer tubes contributes to smooth suspension action (especially at the initial part of the stroke)
• Wrap-around fork tube guards offer effective protection for the sliders
• Lower triple clamp features integrated locating pins to help simplify installation and removal of the front number plate
• One-piece front fender attachment screws feature integrated grommets to simplify installation and removal

2015 Kawasaki KX450F Rear Shock

• 22-position rebound damping adjuster allows precise fine-tuning of the rebound circuit
• Easy adjuster access allows track-side suspension tuning with a minimum of hassle or lost time
• Rear shock features dual compression adjustability, allowing 19-position low-speed and 4 turns of high-speed damping adjustments to be made independently
• Showa rear shock features a large piston and a Kashima coat treatment on the cylinder wall for reduced friction and smoother suspension action

2015 Kawasaki KX450F Aluminum Swingarm

• Tapered “D” shape swingarm is lighter than a comparable box-section unit and provides superior rigidity for its weight
• Features tapered hydroformed spars and forged chain adjusters
• Uni-Trak® rear suspension linkage is mounted below the swingarm to allow precise tuning and maximum rear suspension stroke

2015 Kawasaki KX450F Fuel Tank and Lightweight Aluminum Fuel Pump

• Compact 1.6-gallon fuel tank is formed using a blow molding process
• Fuel pump features a one-piece filter cover and body, eliminating the need for fuel return tube from pressure regulator
• Features a plastic fuel filter cover that wraps around the inlet port and acts as a fuel trap to help ensure a stable fuel supply during vigorous motocross riding

2015 Kawasaki KX450F Efficient Cooling

• High-capacity Denso radiators feature tightly packed cores and a fin design that deliver superior cooling efficiency
• Shroud shape features a slim profile and large cooling outlet hole to help keep excess heat to a minimum
• Radiator louvers feature four small blades set at a shallow angle for minimum overlap and maximum air flow

2015 Kawasaki KX450F Strong and Durable Clutch

• Clutch assembly provides a direct feel and superb control of engagement
• Excellent oil drainage reduces power loss caused by excess oil around the clutch basket
• Friction plates with substantial friction material contribute to fade resistance and long service life
• Clutch case cover features embossed logo and is painted silver, making scuffs and normal wear less noticeable

2015 Kawasaki KX450F Close-ratio 5-Speed Transmission

• 5-Speed transmission and the engine’s broad torque curve gives riders more gear options for maximum drive on a wide range of tracks
• Thick first gear offers excellent durability for launching off the line in high-traction situations

2015 Kawasaki KX450F Powerful Disc Brakes

• Front master cylinder features a knocker-style lever-to-piston interface for excellent feel and superbly consistent performance
• Front brake pads offer a strong braking force and feel
• Lightweight 270mm “oversized” Braking-brand front rotor is squeezed by a powerful twin-piston caliper and features an aggressive petal design to help clear mud and debris
• Lightweight 240mm Braking-brand petal-type rear rotor features the same aggressive petal style as the front rotor and is gripped by a single piston hydraulic rear caliper

2015 Kawasaki KX450F Rider Interface and Styling

• Slender frame helps the bike feel compact and nimble, but tapers to become wider near the rider’s ankles to offer optimum grip and control
• Wide 50mm footpegs can be adjusted to alternate position, 5mm lower than stock
• Dual injected 2-tone, one-piece plastic shrouds and side number plates are great looking, compact and lightweight
• Black triple clamps and black anodized rims – just like Kawasaki’s factory teams
• Green finish on suspension adjusters and engine plugs look like the factory race parts
• Slim seat design uses urethane foam designed to retain its original shape and provide optimum durability

2015 Kawasaki KX450F Additional Features

• Skid plate made of resin material offers great protection without excess weight
• Clutch cable boot features a large quick adjuster, making it easy for riders to adjust clutch play on the fly
• Rear caliper guard helps protect the caliper from damage
• Ribless rear hub and butted spokes offer light weight and excellent durability
• New lightweight axles are lighter by 31 grams front and 32 grams rear

2015 Kawasaki KX450F Optional KX Accessories

• Kawasaki Racing Software Kit allows racers to reprogram the ECU’s data maps for volume of fuel injected and ignition timing to alter engine characteristics to suit rider preference. An ECU setting is available, which can also be used as a data logger, recording up to six hours of data, including engine rpm, degree of throttle opening, engine boost, coolant temp, air temp, ignition timing, fuel adjustments, gear position and system voltage

2015 Kawasaki KX450F Specifications:

  • Engine: Liquid-cooled, four-stroke single with DOHC and four-valve cylinder head
  • Displacement: 449cc
  • Bore x stroke: 96.0 x 62.1mm
  • Fuel Injection: DFI® with 43mm Keihin throttle body
  • Compression ratio: 12.8:1
  • Ignition: Digital DC-CDI
  • Transmission: Five-speed
  • Rake / trail: 27.9 degrees / 4.7”
  • Front suspension / wheel travel: Inverted Showa SFF-Air TAC fork with Triple Air Chamber, hard titanium-coated sliders, 22-position compression and 20-position rebound damping adjustment / 12.4”
  • Rear suspension / wheel travel: UNI-TRAK® linkage system and Showa shock, 19-position 
low-speed and 4 turns high-speed compression damping, 22-position rebound damping and fully adjustable spring preload / 12.4”
  • Front tire: 80/100-21
  • Rear tire: 120/80-19
  • Front brake: Single rigid-mount 270mm Braking petal disc with dual-piston caliper
  • Rear brake: Single 240mm Braking petal disc with single-piston caliper
  • Overall length: 86.4”
  • Overall width: 32.3”
  • Overall height: 50.2”
  • Wheelbase: 58.8”
  • Ground clearance: 13.4”
  • Seat height: 37.8”
  • Curb weight: 247.1 lb
  • Fuel capacity: 1.64 gallons
  • Color: Lime Green
  • MSRP: $8,699

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