Kawasaki KX450F User Manual
2011
Specications:
KX450EBF
Engine Type 4-Stroke, Liquid Cooled, DOHC, 4-Valve, Single
Displacement 449.0 cm³
Bore & Stroke 96.0 x 62.1 mm
Compression Ratio 12.5:1
Fuel System Digital Fuel Injection, Keihin 43 mm Throttle Body
Ignition Digital DC-CDI
Transmission 5-Speed
Rake/Trail 26.7°/ 116 mm
Front Wheel Travel 315 mm
Rear Wheel Travel 315 mm
Front Tire Size 90/100-21 57M
Rear Tire Size 120/80-19 63M
Front Suspension 48 mm Inverted Kayaba AOS with DLC coating and 22-
Rear Suspension Uni-Trak with Adjustable Preload, 22-Way (Low Speed), 2
Wheelbase 1,480 mm
Front Brake Semi Floating 250 mm Petal Disc & Dual Piston Calliper
Rear Brake
Fuel Tank Capacity 7.0 litres
Ground Clearance 335 mm
Seat Height 960 mm
Curb Mass 113.4 kg (Includes full fuel tank and all fluids at correct levels)
Colours Lime Green
(Specications subject to change without notice.)
Way Compression, 20-Way Rebound Damping Adjustment
Turns of Stepless (High Speed) Compression Adjustment,
22-Way Rebound Damping Adjustment, Temperature
Compensating Rebound Adjustment
240 mm Petal Disc & Single Piston Calliper
Key Features:
Easy Starting Digital Fuel Injected Engine
New FIM Approved Mufer
Adjustable Uni-Trak ® Suspension System
2011 KX450F
High-Performance Digital Fuel Injected Engine
Fuel-injected 449 cm³ 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 benets,
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 rst when introduced
on the 2010 KX450F), the 2011 engine receives further
ne-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 ush internal bracing, result in a lighter, stronger
piston.
Improved Shift Feeling
Changes to the shift mechanism result in a rmer 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 specically 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.
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 Fuel Injection ECU
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.
Reduced noise
On European and Australian models, pinched cut-outs in the
silencer chambers direct exhaust gases into the glass-wool
packing, helping to reduce exhaust noise.
• The compact, lightweight ECU, located just in front of the
steering head (behind the number plate), was designed
specically 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 airow 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.
Tail pipe diameter is now 38.3 mm. The revised silencer
internals ensure that strict 2m-max noise regulations are met
(115 dB).
• Ultra-ne atomising injector with 12 holes sprays particles
6
with a droplet size of 60 µm for smooth power deliver and
improved engine at partial throttle.
-HOUR
7
PRESETS
most sample maps
offered in industry
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 an industry leading seven preset settings that can be quickly and easily used to
adjust the ECU to suit track conditions.
• The industry leading KX FI Calibration kit also has 6 hours
of data logging and the choice of either 2D or 3D display.
DATA
LOGGING
only data logging
function in industry
or
DISPLAY
choice of
display
• Lightweight at-bottom aluminium fuel pump is located in
the plastic fuel tank. For 2011, 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 lter 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 (option)
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 analyse
their riding data to further ne-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.
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 efciency 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
efciency.
• 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 efciency at all rpm.
• Lightweight titanium valves (IN: 36 mm; EX: 31 mm)
reduce reciprocating weight and offer high-rpm
reliability.
• Aluminium 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 n 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.
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