Kawasaki KX250F - 2011 Information Manual

Brand: Kawasaki

Model: KX250F - 2011

Category: Motorcycles

Type: Information Manual

This manual is also suitable for

KX250Y 2011

2011 MODEL INFORMATION

MODEL

NAME

KX250F

MARKETING

CODE

KX250Y

INDEX

2011MY KX250F MODEL INFORMATION PAGE 2

OVERVIEW - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - P.3

KEY FEATURES - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - P.4

POWERFUL, HIGH-REVVING FUEL-INJECTED ENGINE - - - - - - - - - - - - - - - - - - - - - - - - P.4

HIGH-SPEED CHASSIS WITH FACTORY-STYLE COMPONENTS & TUNING - - - - - - - - - - P.11

ADDITIONAL FEATURES - - - - - - - - - - - - - - - - - - - - - - - - - - - - - P.18

COLOURS - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - P.19

SPECIFICATIONS - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - P.20

OVERVIEW

2011MY KX250F MODEL INFORMATION PAGE 3

Fi AND FACTORY TUNING KEEPS EXPERT RIDERS

AT THE FRONT

The KX250F base package provides an excellent platform for race-experienced riders to

win in the top classes.

The design of the highly rigid aluminium frame, suspension components and settings,

focused on ensuring control is maintained during high-speed riding – especially in straight

lines – to enable experienced racers to ride to their maximum potential and to deliver

holeshot-winning performance. The later is a key factor that can mean the difference

between running up front and winning, or getting stuck mid-pack. Chassis geometry and

the high-revving 4-stroke engine’s wide powerband were designed to maximise rear

wheel traction and the combination is a proven race-winner, with multiple UK and

European wins in addition to AMA Supercross Lites and Motocross Lites championships

to its credit.

To ensure the Lime Green racers continue to run at the front, Kawasaki engineers have

made a number of engine and chassis changes to further increase the KX250F’s winning

potential.

KEY FEATURES

2011MY KX250F MODEL INFORMATION PAGE 4

POWERFUL, HIGH-REVVING FUEL-INJECTED

ENGINE

Tuned to best suit race-experienced riders, the 249 cm3 liquid-cooled, 4-stroke single’s

wide powerband focuses on high-rpm performance and extends way into the over-rev.

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 KX250F), the

2011 engine receives fuel injection and a number of changes for even more power,

stronger low-mid range torque (most noticeable when riding through the whoops, landing

jumps and coming out of tight turns, it allows riders to shift less often, reducing fatigue

and enabling quicker lap times throughout the moto), more accurate shifting and a quieter

exhaust note.

Factory-racer engine tuning

High-performance piston, features the

same design used on our factory

racers and 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.

A new piston crown, revised to suit chamfering of the squish area, offers increased

high-rpm and over-rev performance.

Intake camshaft with revised sprocket/shaft arrangement retards intake valve timing

1˚, to suit the new fuel-injected engine.

Open 10MY:41˚ BTDC 11MY:40˚ BTDC

A new spark plug protrudes 1.4 mm deeper into the combustion chamber, improving

combustion efficiency.

Intake ducting has about 10% greater volume, resulting in improved response

(especially in the ultra-low rpm range).

KEY FEATURES

2011MY KX250F MODEL INFORMATION PAGE 5

The revised intake ducting and new deep-protrusion spark plug not only offset the

drop in low-mid torque that comes from a change to fuel injection, performance is

actually improved in this range.

Revised final reduction ratio offers improved engine feel. The shorter gearing

(13/48T >> 13/50T) further accentuates the increased low-end torque.

Cylinder height reduced (36.5 mm >> 36.3 mm) to suit the new piston and higher

compression ratio: now 13.5:1 (previously 13.2:1).

Exhaust pipe is longer (480 mm >> 510 mm) to suit new engine characteristics.*

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 familiar need to adjust engine settings to suit

track and climate conditions.

Ensuring quick starting without a battery was a prime directive when developing this

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.

A 43 mm throttle body makes use of a

progressive throttle link to deliver

airflow in much the same way as

would an 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.

Lightweight throttle body is approximately half the weight of an FCR carburettor – a

weight saving of about 600 g.

KEY FEATURES

2011MY KX250F MODEL INFORMATION PAGE 6

To ensure the high-rpm engine’s

demand for a high flow of gas in a

short period is met, the KX250F’s

injector features larger holes than that

used on the KX450F. A fine atomising

injector with 4 holes disperses spray

particles with a droplet size of 120

μm. Fuel flow is about 20% greater

than on the KX450F.

The newly designed fuel pump,

located in the fuel tank, is a

lightweight aluminium construction.

(Fuel tank capacity is now 7.2 litres.)

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 accessory)

The KX Fi Calibration Kit is the same kit used by Kawasaki’s works teams and Team

Green dealers in Europe and the U.S. The kit enables Team Green dealers, Kawasaki

race teams and 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

required.

While the kit is designed to satisfy racers and expert riders, it is designed to be

simple to use:

- the ECU controller mounts behind the number plate for easy access

KEY FEATURES

2011MY KX250F MODEL INFORMATION PAGE 7

- 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 retarded, 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 (left). Settings can be increased or

decreased

from the base according to rider preference (right).

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.

KEY FEATURES

2011MY KX250F MODEL INFORMATION PAGE 8

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.

KEY FEATURES

2011MY KX250F MODEL INFORMATION PAGE 9

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.

Less mis-shifts

A longer ratchet lever causes the ratchet to turn a greater amount with each shift

(53o >> 60o), reducing the chance of mis-shift.

A lighter ratchet lever return spring ensures that shift lever weight feel remains the

same.

Reduced noise

On European models, pinched

cut-outs in the silencer chambers

direct exhaust gases into the

glass-wool packing, helping to reduce

exhaust noise. The revised silencer

internals ensure that strict 2m-max

noise regulations are met (115 dB).

On North American models, revised internal construction results in a quieter silencer

that clears stricter 94 dB noise regulations.

Additional performance-oriented 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.

KEY FEATURES

2011MY KX250F MODEL INFORMATION PAGE 10

Lightweight titanium valves (IN: 31 mm; EX: 25 mm) reduce reciprocating weight

and offer high-rpm reliability. The ultra-light valves have extremely thin valve stems

on par with those found in supersport machines. The intake valves feature thicker

heads for increased strength and both intake and exhaust valves are formed from a

highly rigid, titanium material.

Crank web design increases offsetting moment for a high crankshaft balance factor.

At close to 60%, the balance factor of the ’11 KX250F is on par with our factory

racers. The high balance factor contributes to reduced engine vibration, smoother

power delivery and increased

performance in the mid-high rpm range.

32 mm thick, 117.8 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.

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.

KEY FEATURES

2011MY KX250F MODEL INFORMATION PAGE 11

HIGH-SPEED CHASSIS WITH FACTORY-STYLE

COMPONENTS & TUNING

The KX250F’s slim aluminium 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 2011, the high-speed chassis benefits from a new Separate

Function front Fork (SFF) with greatly reduced friction that offers increased riding comfort

and improved suspension performance. In addition to enhanced handling offered by the

SFF’s improved left/right balance, increased chassis flex and revised frame rigidity

balance offer lighter handling and increased turning performance. The highly acclaimed

high-speed stability of its predecessor remains unchanged.

Lighter-handling chassis

While the frame remains essentially the

same as that of the 2010 model, revised

rigidity balance results in a frame with

designed in moderate lateral flex.

Frame’s front and side hangers (engine mounting brackets), previously aluminium,

are now formed from steel, and are thinner (front: t6.0 mm >> t4.5 mm; side: t8.0

mm >> t4.5 mm).

The resultant increased lateral chassis flex enables lighter turning.*

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

Reduced fork offset (23.5 mm >> 22.5 mm) also contributes to the lighter handling,

enhanced cornering accuracy and more planted feel of the front wheel. Additionally,

it also gives the bike a more compact feel.

Superior rear-wheel traction

KEY FEATURES

2011MY KX250F MODEL INFORMATION PAGE 12

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.

Race-oriented suspension: Separate Function Front Fork

Showa’s Separate Function Front Fork

(SFF) makes its first appearance on a

mass-production

motocrosser. The SFF separates damping

and shock absorption duties:

> Left fork tube: damping assembly

> Right fork tube: spring

The configuration offers both smooth action

and firm damping performance – a

combination

difficult to achieve with a conventional fork.

With only one spring, the friction generated between the spring(s) and fork inner

tube(s) is greatly reduced (approximately 25% less), resulting in extremely smooth

action throughout the fork stroke. (Illustrations A, B)

KEY FEATURES

2011MY KX250F MODEL INFORMATION PAGE 13

Being able to use a larger damper

piston not only enables smoother

action and makes firm damping

performance possible. (Illustration C)

Removing the damper assembly from

NEW the right fork tube frees up

space for a preload adjuster. Having a

preload adjuster greater simplifies the

task of setting fork preload or front

height. (With a conventional fork, only

the rear could be adjusted easily;

adjusting the front required fork tubes

to be disassembled and the use of

collars and special tools. With SFF,

both the front and rear preload/height

can be set quickly and easily.)

In addition to preload adjustment, the

racer-friendly SFF also facilitates

other maintenance chores like

adjusting damping and changing

springs.

KEY FEATURES

2011MY KX250F MODEL INFORMATION PAGE 14

SFF offers improved left/right balance, which greatly enhances handling. Locating

the heavy spring in the right tube (and fine-tuning the left and right tube strength)

better offsets the previously unbalanced weight of the brake caliper and disc on the

left side.

A restrictor added on the damper

assembly side and a joint rod comp

added on the spring side ensure that

natural character is maintained.

Placement of the restrictor can be

used to change damping

characteristics; it contributes to

idealised damping character. The joint

rod comp ensures even left/right

damping force and contributes to

ideal fork rigidity.

A super-hard titanium coating on the

outer surface of the inner fork tubes

reduces sliding friction (and stiction)

and improves action, contributing to

the smoother ride. The increased

surface hardness of the dark navy

blue coating also helps to prevent

scratches and damage to the tubes.

(The KX250F is the only motocrosser

in its class to feature this race-ready

coating as a standard feature.)

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.

Race-oriented rear suspension

Rear shock damping settings, revised

to match the new SFF, offer

improved action and increased

absorption performance.

The rear shock features dual compression adjustability, allowing high-speed and

low-speed damping to be tuned separately.

KEY FEATURES

2011MY KX250F MODEL INFORMATION PAGE 15

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

Among the KX250F’s numerous factory-style components are its front and rear

petal disc brakes. 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.*

Factory-style Renthal (standard-type)

aluminium handlebars are standard

equipment.

Rib-less rear hub and butted spokes reduced unsprung weight.*

Rims are coated in black alumite1 – just like our factory racers.*

Fork and rear shock adjusters have a blue alumite1 finish like our US factory racers.*

KEY FEATURES

2011MY KX250F MODEL INFORMATION PAGE 16

Factory-style graphics complement the KX250F’s highly tuned performance.*

Rider interface

Designed with rider ergonomics in mind, the bodywork components offer the rider a slim

interface, the natural position makes 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.

The seat uses a slip-resistant top surface for good grip when seated and smooth

sides for excellent rider mobility.

KEY FEATURES

2011MY KX250F MODEL INFORMATION PAGE 17

Revised pattern for the seat sides

offers 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.

The 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.*

ADDITIONAL FEATURES

2011MY KX250F MODEL INFORMATION PAGE 18

Engine

Electrofusion treatment on cylinder

bore results in a surface with good 22

oil retention. Further, the molybdenum

on the surface of the cylinder bore

helps resist scorching, contributing to

durability.

Chassis

The alloy swingarm uses a cast front section, tapered hydroformed spars and

forged chain adjusters.

Swinging arm is longer to accommodate the larger rear sprocket, and is now

common with the KX450F. The chain is also longer: 112 links >> 114 links.

Large synthetic skid plate offers great protection with minimum weight.*

Front chain guide (chain slider) uses a thicker plastic lining, offering longer wear life.*

Other

Optional engine parts include magneto rotors with different inertias (8.5, 9.5 kg.cm2;

STD: 9.0 kg.cm2) and a 12T output sprocket (STD: 13T).

Optional chassis parts include handlebar holder for a ø28.6 mm bar (STD: ø22.2

mm), aluminium and steel rear sprockets (48-52T; STD: 50T), solid petal brake

rotors for wet races, and different springs for the front fork (8.7, 9.1, 9.5 N/mm; STD:

9.1 N/mm) and rear shock (47, 48.1, 49, 50, 51, 52, 53, 53.9 N/mm, STD: 51

N/mm).

An Fi indicator lamp (available as an

option) warns of any problem with the

Fi system.

COLOURS

2011MY KX250F MODEL INFORMATION PAGE 19

Lime Green with factory-style graphics

SPECIFICATIONS

2011MY KX250F MODEL INFORMATION PAGE 20

ENGINE

Engine type Liquid-cooled, 4-stroke Single

Displacement 249 cm³

Bore x stroke 77.0 x 53.6 mm

Compression ratio 13.2:1

Valve/Induction system DOHC, 4 valves

Fuel system Carburettor: Keihin FCR-MX37

Ignition Digital AC-CDI

Starting Primary kick

Lubrication Forced lubrication, semi-dry sump

DRIVETRAIN

Transmission 5-speed, return

Final Drive Chain

Primary reduction ratio 3.350 (67/20)

Gear ratios: 1st 2.142 (30/14)

Gear ratios: 2nd 1.769 (23/13)

Gear ratios: 3rd 1.444 (26/18)

Gear ratios: 4th 1.200 (24/20)

Gear ratios: 5th 1.045 (23/22)

Final reduction ratio 3.692 (48/13)

Clutch Wet multi-disc, manual

FRAME

Frame type Perimeter, aluminium

Wheel travel, front 315 mm

Wheel travel, rear 310 mm

Tyre, front 80/100-21 51M

Tyre, rear 100/90-19 57M

Rake/Trail 27.7°/122.3 mm

Steering angle, left / right 42° / 42°

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Kawasaki KX250F - 2011 Information Manual

Brand: Kawasaki

Model: KX250F - 2011

Category: Motorcycles

Type: Information Manual

This manual is also suitable for

KX250Y 2011

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Kawasaki KX250F - 2011 Information Manual

This manual is also suitable for

Kawasaki KX250F - 2011 Information Manual

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