Kawasaki KX450F User Manual

2011

Specifications:

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-
	Way Compression, 20-Way Rebound Damping Adjustment
Rear Suspension	Uni-Trak with Adjustable Preload, 22-Way (Low Speed), 2
	Turns of Stepless (High Speed) Compression Adjustment,
	22-Way Rebound Damping Adjustment, Temperature
	Compensating Rebound Adjustment
Wheelbase	1,480 mm
Front Brake	Semi Floating 250 mm Petal Disc & Dual Piston Calliper
Rear Brake
	240 mm Petal Disc & Single Piston Calliper
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

(Specifications subject to change without notice.)

Key Features:

Easy Starting Digital Fuel Injected Engine

New FIM Approved Muffler

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 lowthrough 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 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.

Tail pipe diameter is now 38.3 mm. The revised silencer internals ensure that strict 2m-max noise regulations are met (115 dB).

Improved Shift Feeling

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 60 µm for smooth power deliver and improved engine at partial throttle.

•Lightweight flat-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 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 (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 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.

7	6-HOUR	or
	DATA	DISPLAY
PRESETS	LOGGING
most sample maps	only data logging	choice of
offered in industry	function in industry	display

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.

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.

•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 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.