| 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 |
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| 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 |
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| 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 |
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| 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 |
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| 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 |
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| 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 |
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| 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 |
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| 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 |
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| 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 |
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| 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 |
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| 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 |
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| 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 |
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| 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 |
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| 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 |
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| 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 |
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| 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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