Introduction
More AMA Lites Championships than
any Motorcycle in History!
It's an old refrain: The factory guys get all the good stuff.
Their bikes are faster, lighter and just plain tricker than the
motocrossers you can buy off the showroom floor. There's some
truth there. But that's changing. The gap between production
and factory-prepped motocrossers has never been narrower. And
with the introduction of Kawasaki's massively reworked 2011 KX™250F,
that gap just shrank a little more.
All told, there are nearly 30 upgrades to the new KX250F, all
of which reflect the stunning level of testing and development
happening behind the scenes at Kawasaki's R&D and race teams.
And Kawasaki does this for one reason: To put you on the fiercest,
most capable motocrosser in the industry.
When reworking the new KX250F, engineers started with what's
arguably already the gold standard in 250-class racing
the 2010 KX250F. Just ask Christophe Pourcel and Jake Weimer,
who won the 2010 AMA East and West Lites titles, respectively,
on their Monster Energy™/ Pro Circuit / Kawasaki-backed
KXs. Or the long list of enthusiast magazine shootouts that picked
the 2010 KX250F as the best motocrosser in its class.
For 2011, the goal was an even faster and more ridable KX250F.
On the more powerful side of the equation are loads of engine
modifications, all of which have made the latest KX an absolute
corner-to-corner screamer. The big news is the addition of Digital
Fuel Injection (DFI®) that not only helps produce stunning
and more useable power, but also makes tuning a much
easier proposition. The system, basically identical to the one
fitted to the 2011 KX450F, automatically adjusts to suit track
and climate conditions, and offers consistent fuel metering and
response even when the going gets rough, such as when landing
off jumps or slamming through the whoops. The simple and highly
efficient DFI system incorporates a compact and lightweight Electronic
Control Unit (ECU), a 43mm throttle body, a lightweight aluminum
fuel pump and an ultra-fine atomizing injector. Set at a 45-degree
angle for optimum mid-range power, the injector precisely metered
fuel directly into the intake tract for smooth power delivery
and highly accurate engine response throughout the entire rpm
range. The 250F's injector actually flows more fuel than the
450F's unit due to the 250F engine's higher speeds, while airflow
through the system is actually higher than through the 2010 model's
carburetor setup.
Designed specifically for motocross, the KX250F's lightweight
DFI system requires no battery; the engine can be started within
three rotations of the crankshaft using only the electricity
generated through the initial stroke of the kickstarter. What's
more, an optional ECU Setting Tool allows racers to select from
several different ECU data maps, or fine tune a custom map that
alters fuel injection and ignition timing to suit different tracks
and conditions. The tool can also be used as a data logger, recording
up to six hours of data, including engine rpm, degree of throttle
opening, coolant and air temperatures, ignition timing, fuel
adjustments, gear position and system voltage.
You'll find more significant changes farther downstream, such
as higher compression now 13.5:1 vs. 13.2:1 via a
modified cylinder and changes to the top of the exclusive Bridged-Box
Bottom piston. The intake camshaft now produces higher valve
lift, while the intake valve spring is stronger to handle the
extra load. The crankshaft's rotational inertia has been slightly
modified to better match the new engine's characteristics, while
a slightly longer spark plug design and a new coil offering
a hotter and longer-duration spark improves combustion
performance. Transmission and final-drive ratios have been altered
slightly to match the engine's newfound response, and a modified
shifting mechanism allows you to access those speeds more easily
and smoothly. There's 10% more air-cleaner duct volume for better
breathing, and on the exhaust side, a longer head pipe gives
the engine a touch more low-end power, while a higher-volume
muffler assembly lowers noise to comply with the 94 db AMA Pro
Racing limit, while retaining optimum power production up top.
The chassis has been massaged every bit as thoroughly as the
engine, with Kawasaki's new Separate Function Fork (SFF) leading
the list of changes. Unlike a conventional fork design, where
each fork leg handles both springing and damping, the SFF separates
spring and damping functions for improved performance, 25 percent
less friction, lower weight and easier adjustability. The right
leg accommodates the spring side of the equation, incorporating
a larger main spring/rod assembly than traditional forks, plus
a small amount of oil for lubrication. Spring preload is now
adjustable via a blue-anodized adjuster on the right leg's cap.
The left leg handles damping duty, with only its cartridge damper
assembly and fork oil inside the tube. Rebound and compression
damping are adjustable on the fork tube. In addition to the natural
reduction in friction provided by the SFF design, the KX250F's
inner fork tubes are titanium nitride coated to reduce friction.
Lower friction and better overall fork action are keys to the
new fork's performance, and they are traits you'll appreciate
the first time you charge into a bump-infested corner at speed.
Fork offset has also been reduced by a full millimeter for lighter
handling and quicker steering response.
Out back, the rear shock incorporates revised damping settings
that more closely match the SFF's performance. The result is
even more wheel and chassis control while ripping across a set
of whoops or shrieking through that fast, rutted corner leading
onto the front straight. Like the KX450F, the new 250F gets a
reworked seat with grippier material along the sides for improved
rider grip while standing when the action gets hot and heavy.
The rest of the package includes the same top-tier components
that have put the KX250F atop the podium for years. The KX250F's
aluminum perimeter frame, with its lightweight blend of forged,
extruded and cast parts, has the chassis balance, rigidity and
durability experienced riders want and need, and locates the
engine, rider and pivot points where they perform best.
Designed with rider ergonomics foremost in mind, the KX250F's
bodywork offers riders a slim interface and a natural positioning
that make going fast a simple affair. The sleek bodywork components
include one-piece plastic shrouds and side number plates. The
upgraded seat provides excellent seated grip and rider mobility,
and features firm urethane foam to hold its shape longer. Chassis
protection bits include the large, resin skid plate, rear caliper
guard and a redesigned chain guide with approximately 2.5 times
more durability than the 2010 unit.
The KX's 249cc, liquid-cooled, four-stroke engine is a veritable
powerhouse, and features an electrofusion cylinder treatment
on the cylinder bore, a crankshaft balance factor of nearly 60
percent (on par with Pourcel and Weimer's factory racebikes),
for reduced vibration and smoother power delivery, a highly durable
yet slick-shifting transmission, stronger-than-ever
crankcases and a level of reliability that'll keep you out there
and on-track all season long. It's been rated the best engine
in its class by various magazine editors, and you'll understand
their thinking after your very first ride.
The rest of the KX250F package is every bit as impressive as
the engine and chassis. Aside from the sort of fit and finish
you expect from Kawasaki, there's also a premium-quality Renthal
aluminum handlebar included standard, black alumite-coated aluminum
wheels that are both light and strong, a ribless rear hub and
butted spokes that further reduce unsprung weight, and factory-style
graphics that finish things off nicely and highlight the KX250F's
amazing on-track abilities.
Racers who ride their KX250F at designated events are eligible
to receive support from Team Green, Kawasaki's amateur racing
support program. Each year, Team Green™ provides regional
support vehicles and highly trained technicians at more than
100 events throughout the United States, offering technical information
and assistance to those who race Kawasaki products. Kawasaki
also offers a comprehensive contingency program for amateur and
professional riders who place well at designated events.
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Features
At a Glance...
- New Digital Fuel Injection (DFI) system
- New Showa Separate Function Fork (SFF) divides spring and damping
functions; springing in the right leg and damping in left provide
less friction, better performance and easier adjustability
- Increased engine performance via higher compression and exhaust/intake
changes
- High-performance piston featuring Bridged Box-bottom design
- Stainless steel exhaust features longer header section and
larger-volume muffler
- Revised suspension settings front and rear aimed at race-experienced
riders
Higher Performing, High-revving Engine
- 249cc, liquid-cooled, four-stroke, four-valve, single-cylinder
DOHC engine delivers hard-hitting power across the rpm range
- Modified intake valve timing and cam profile for increased
valve lift improves high-rpm power production
- Intake valve spring tension increased to control more radical
cam timing
- Digital Fuel Injection (DFI) system allows consistent fuel
delivery, quick starts and easy adjustability
- Engine tuned to achieve the widest possible torque band to
maximize traction through a greater percentage of the rev range
- Race-experienced riders able to harness high-rpm performance
that extends way into the over-rev
- Sprocket-style chain drive roller helps reduce the effect of
driveline lash and engine braking for smoother and faster corner
entries
- Crank web design features a balance factor on par with the
factory racers for reduced engine vibration, smoother power delivery
and increased performance in the mid-high rpm range
Digital Fuel Injection (DFI) System
- Same basic system that's fitted to the KX450F
- 43mm throttle body assembly with 20 percent higher-flow injector
than the KX450F's injector
- Intake airflow is higher than on carburetor-equipped 2010 model
- Progressive throttle link; opens more quickly after 3/8 open
position
- Simple and efficient system: No battery, fuses or relays
- Improves engine response across entire rpm range
- Offers easy engine starting
- Prevents engine hesitation after landing from jumps and other
high-impact situations
- Optional Calibration Kit allows easy tunability
- Optional FI Indicator Light allows the DFI system to communicate
diagnostic information
Bridged Box-bottom Piston
- Light and strong piston shares same design as the factory racers,
with a revised crown for higher compression. Also features fully
flush internal bracing
- Short piston pin reduces reciprocating weight
Lightweight and Efficient Top End
- Lightweight, highly rigid, titanium 31mm intake and 25mm exhaust
valves reduce reciprocating weight and offer high-rpm reliability
- Ultra-light valves have extremely thin valve stems on par with
those found in supersport machines; intake valves feature thick
heads for increased strength
- Intake ports designed for peak performance at all rpm, especially
in the high-rpm range
- Special coating applied to intake port cores during casting
gives the intake ports extremely smooth surfaces and optimum
intake efficiency across the rev range
- Silicon-coated head gasket provides excellent sealing
Enhanced Durability and Reliability
- Electrofusion treatment on cylinder bore improves surface oil
retention, while the molybdenum coating on the cylinder bore
surface helps resist scorching, further contributing to durability
- Wide big-end bearing features a thick copper plate on its cage
and a long crank pin for increased reliability
- Oil pump rotors offer a high degree of reliability and durability;
a large feed pump rotor maximizes oil flow, while a smaller scavenge-pump
rotor reduces mechanical losses
New Stainless Steel Exhaust System
- Stainless steel construction offers extra durability
- Longer header pipe section for improved low and mid-range response
- Higher-volume muffler assembly quiets emissions to 94 dB noise
regulations while retaining power production
- Joint between pipe and muffler offers excellent sealing, while
a rubber damper collar on the rear silencer mount equals serious
durability
Efficient Cooling System
- Thick and wide radiators are strong and offer excellent resistance
to mud buildup while providing superb cooling performance
- Cylinder head water jacket routes coolant to the front of the
cylinder head for even cooling
Transmission and Shifting Reliability
- Third and fourth input gears have large dogs to help prevent
wear
- Revised ratchet and lever angle for more positive shifting
- Revised internal ratios for second and fourth gear better match
new engine power delivery
- New 50-tooth rear sprocket helps capitalize on the engine's
torque delivery
- Strong, beefy crankcases feature additional material around
the engine mounts to help increase long-term durability
- Clutch cable holder is integrated with the crankcase for accurate
feel at the clutch lever
- Scavenge oil filter screen can be accessed without splitting
the crankcases, facilitating easier maintenance
Quick-turning Chassis
- Utilizes a low-rigidity steering stem for lighter handling
- The KX250F's slim and lightweight aluminum perimeter frame
is composed of forged, extruded and cast parts
- Center of gravity and key dimensions such as swingarm pivot,
output sprocket and rear axle locations designed to increase
forward drive with minimal rear-end squat
- Upper engine mounts on head cover sides increase overall rigidity
Race-oriented Suspension
- Revised race-oriented suspension damping settings optimize
front/rear balance
- New Separate Function Fork (SFF) separates springing and damping
functions for less weight, better performance, less friction
and easier adjustability
- Fork now allows external spring preload adjustability
- Super-hard titanium coating on the outer surface of the inner
fork tubes reduces friction and improves suspension action. The
increased surface hardness also helps prevent scratches and tube
damage
- Friction-reducing Kashima Coat treatment on the inside of the
outer fork tubes contributes to smoother suspension action
- Wrap-around fork tube guards provide greater protection for
the inner tubes
- Revised shock damping settings offer increased absorption performance
and greater stability on corner entry thanks to reduced rear-end
kicking
- Features Kashima Coat on the inside of the shock reservoir
for reduced friction and smoother suspension action
- Rear shock features dual compression adjustability, allowing
high-speed and low-speed damping to be tuned separately
Superior Rear-wheel Traction
- Swingarm features optimum internal bracing and flex characteristics
for improved cornering performance
- Alloy swingarm uses a cast front section, tapered hydroformed
spars and forged chain adjusters
- Uni-Trak® rear suspension system mounts the suspension
arm below the swingarm, allowing more rear suspension stroke
and precise tuning
- Linkage ratios for the Uni-Trak rear suspension match rear
shock damping settings to achieve maximum rear wheel traction
Rider Interface
- Bodywork components offer the rider a slim interface, making
it easy for racers to feel comfortable and go fast
- Formed using a double-injection molding process, the two-tone
shrouds offer a slim design
- Side number plates also two-toned and contribute to the slim
package
- Right side panel has an added passageway to help cool the silencer
- Frame is wider at the ankles to offer better grip and narrows
near the bend below the seat to allow a slim riding position
- Slim seat features firm urethane, which keeps its original
shape longer
- Seat has a slip-resistant top and side surface for good grip
when seated and while standing
- 50mm wide (front-to-rear) footpegs offer superb grip and feel
at the pegs
- Clutch cable boot features a large quick adjuster, making it
easy for riders to adjust play in the clutch cable while on the
fly
- Throttle grip has a one-piece collar that provides additional
stability during throttle operation
- Lightweight short-length grips feature a pattern designed to
provide excellent grip
Factory-style Components
- Black alumite-coated rims, just like the factory racers
- Lightweight rims offer maximum strength and weight savings
- Thick and rigid front fender
- Rear brake pad material offers powerful braking performance
- Front and rear petal brake discs help reduce unsprung weight,
and the wave shape helps clean the brake pads for more efficient
braking performance
- Rear caliper guard protects caliper from damage
- Ribless rear hub and butted spokes further reduce unsprung
weight
- Renthal aluminum handlebar is standard equipment
- Factory-style graphics complement the KX250F's highly tuned
performance
Additional Features
- Large front brake lever boot offers increased protection against
debris
- Newly designed and more durable chain guide utilizes a thicker
wear pad for longer life
- Large resin skid plate offers great protection with minimum
weight
Optional Accessories
- Optional DFI Calibration Kit allows custom tuning
- Optional FI Indicator Light allows the DFI system to communicate
diagnostic information
- Engine parts include magneto rotors with different inertias
and a 12-tooth output sprocket
- Optional chassis parts include handlebar holder for a 1 1/8-inch
handlebar, 46
- to 50-tooth aluminum and steel rear sprockets, solid petal
brake rotors, different fork and shock springs and manual decompression
lever and cable
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Technical Specifications
Engine: Four-stroke single with
DOHC and four valves
Displacement: 249cc
Bore x stroke: 77.0 x 53.6mm
Cooling System: Liquid
Fuel injection: 43mm Keihin throttle body
Compression ratio: 13.5: 1
Ignition: Digital DC-CDI
Transmission: Five-speed with wet multi-disc manual clutch
Final drive: Chain
Frame Type: Aluminum perimeter
Rake/Trail: 28.2 degrees / 4.7 in.
Front suspension / wheel travel: 47mm inverted Showa SFF telescopic
fork with spring preload adjustability and 22 position compression
and 20 position rebound damping adjustability/ 12.4 in.
Rear suspension / wheel travel: Uni-Trak® linkage system
and Showa shock with 19 position low-speed and stepless high-speed
compression damping, 22 position rebound damping and fully adjustable
spring preload / 12.2 in.
Front Tire Size: 80/100-21
Rear Tire Size: 100/90-19
Front brakes: Single semi-floating 250mm petal disc with dual
piston caliper
Rear Brakes: Single 240mm petal disc with single-piston caliper
Overall length: 85.4 in.
Overall width: 32.3 in.
Overall height: 50.0 in.
Wheelbase: 58.1 in.
Ground Clearance: 13.0 in.
Seat height: 37.2 in.
Curb weight: 232.7 lbs.
Fuel capacity: 1.9 gal.
Color Choices: Lime Green
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