| All New for 2010 |
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- The all-new, Bilateral Beam frame is specific to the
250 and is more compact than the previous generation
chassis. This places the rider closer to the front
wheel, which delivers superb rigidity balance for
unmatched lightweight handling and cornering. This
nimbleness lets the rider get on the gas sooner out
of corners and cross the finish line with less fatigue
– even on long motos.
- The optimized engine delivers a new level of power in
low-to-midrange, with a great torquey feel, exactly
where riders want it. That is due to the new straight
intake boot that enhances breathing, new carburetor
that provides excellent throttle response and fuel
atomization, and redesigned valve train components
that reduce inertial mass and boost low end torque.
Exhaust is also enhanced with a new D-shaped
exhaust port and newly designed exhaust system.
Ongoing refinement to the suspension and engine
produces an amazingly balanced, light-handling
machine with performance that’s accessible to all
levels of riders.
- All new styling emphasizes the bike’s light weight
and nimble handling character. The sharp, horizontal
lines set the bike apart, with a clean, aggressive
look.
- KYB® suspension has been recalibrated front and
rear and is tuned to work with the new Bilateral
Beam frame for unmatched handling. The clutch
lever has a lighter pull feel even though the clutch
has stronger engagement. The new clutch also has
a wider engagement range that will give riders an
advantage off the line. . . shift after shift, moto after
moto.
- There’s no disputing the YZ250F’s unmatched
four-stroke prowess – it was the 1st four-stroke
250 motocross bike on the market, the 1st to win an
international race, the 1st to win an AMA® Supercross
® and the 1st to take an AMA® U.S. Supercross
Championship® title, as well as the first to win an
AMA® National race.
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- The valve spring retainers are now lightweight aluminum instead of steel, and valve spring pressure is lighter for reduced valve opening force. This contributes to superior low-to-mid range torque characteristics due to less power-robbing friction. There’s also a new, higher lift cam profile, while valve stem ends are chromium-nitride coated for exceptional reliability and reduced maintenance.
- The exhaust port shape has a “D” shape instead of round.
This increases velocity through the port for excellent throttle response, while enhancing the power feeling of the engine.
- The newly designed radiator is lower and further back and the oil
tank is more compact and repositioned to achieve greater mass
centralization.
- The carburetor bore has a new venturi shape, plus there’s recalibrated
jetting and a new accelerator pump. This translates to
impressive response when the rider snaps open the throttle, and
contributes to superb torquey low-to-midrange power characteristics.
- The intake boot offers a straight, smooth tract for excellent
engine breathing and more power. The airbox is reshaped to tuck
neatly into the Bilateral Beam frame.
- The exhaust pipe has been carefully tuned to optimize engine
power, with a muffler that’s 50mm longer and with a narrower
core – a design that lets the YZ250F comfortably meet the latest
noise standards without sacrificing power.
- Engineers were able to increase the clutch spring load for stronger
engagement, yet, thanks to a recalibrated clutch actuation
arm cam ratio, lever pull is actually lighter than before.
- Third and fourth gear ratios are slightly taller, and third, fourth,
and fifth gears are stronger than ever with new drive dog shapes
for positive engagement. That gives riders a strong gearbox that’s
been carefully matched to engine power characteristics.
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- The Bilateral Beam frame is crafted from a carefully chosen combination
of forged and extruded aluminum pieces – 20 in all – all
welded together to provide unmatched rigidity balance.
- The KYB® speed-sensitive front fork delivers exceptional damping
feel, responsiveness, and bump absorption characteristics.
Damping settings are revised, the piston rods have a new surface
treatment, and the oil seal is a new design.
- The 4-way-adjustable KYB® rear shock has been redesigned to
make the most of the Bilateral Beam frame design. It’s lower in
the frame for excellent mass centralization, and has new damping
characteristics.
- The new tank, seat, and rear fender are flat and the relationship
between handlebars, pegs, and seat result in a natural, more
forward riding position that facilitates rider movement. The fuel
tank has been moved toward the center of the bike for mass
centralization. The ProTaper® bars are four-way adjustable, and
handlebar mounts and footpegs are 5mm higher to optimize rider
position on the new chassis.
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- The CDI unit has revised ignition mapping to match new engine
intake and exhaust specs.
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