All new for 2010

Engine:

• The rearward-slanted engine allowed engineers to design
straight intake and exhaust ports, creating the most direct path
for air flow into the fuel-injected engine for incredible performance.
• The YZ450F uses a battery-less fuel injection system with a
12-hole injector for superb fuel atomization. The 44mm Keihin®
throttle body is designed for easy starting, with an integrated
cold start and idle speed adjustment knob. Yamaha FI provides
optimal air/fuel mixtures in all altitudes and wide range of temperatures
for outstanding throttle response.
• 14 volt / 110W high output generator powers the battery less fuel
injection system.
• 4-titanium valve cylinder head with a “pent-roof” design combustion
chamber provides excellent combustion efficiency and
unequalled power output.
• Intake and exhaust camshaft profile changes to increase valve
working angle and valve lift for most excellent performance at
all rpm.
• The bigger 97.0mm bore and shorter 60.8mm stroke, along with
a higher 12.5:1 compression ratio, create a combustion chamber
that delivers really impressive power.
• The air filter case is changed to accommodate the new engine
layout. Putting it up front keeps dirt and dust kicked up from the
rear tire away from the intake system.
• New “tornado-style” exhaust header with resonator efficiently
scavenges exhaust gasses and helps the engine achieve its
exceptional low-to-mid range torque characteristics, while the
150mm-longer muffler comfortably meets the latest noise standards
without a sacrifice of power.
• Clutch and transmission components have been thoughtfully
revamped to give the rider great shifting feel.
CHASSIS/SUSPENSION:
• The aluminum Bilateral Beam frame is crafted from a carefully
chosen combination of forged and extruded aluminum, 16 components
in all, for the right rigidity balance and light weight. A very
symmetrical chassis design promotes nimble handling, letting
riders enter and exit corners as quickly as possible to put the
competition behind them.
• New skid plate is constructed from tough polypropylene for great
protection and low weight.
• The swingarm and rear shock are redesigned, with the shock
mounted along the central axis of the frame, taking advantage
of the space no longer needed for the front-mounted airbox. This
optimized combination delivers exceptionally linear performance
for excellent bump absorption and awesome cornering ability.
• The KYB® Speed Sensitive front fork has 10mm longer stroke for
excellent feel and shock absorption.
• KYB® rear shock with large capacity piggy back reservoir and
50mm piston for more consistent damping control.
• New fuel tank is positioned underneath the seat, contributing to
the centralized mass. The seat is long and flat for to allow free
rider movement.
• New rear sprocket shape has a trick appearance and is light
weight.
• The triple clamps are redesigned, with a change in offset from 25
to 22 mm for unequalled cornering performance. The ProTaper®
bars are four-way adjustable to accommodate a wide range of
riders.
• The front and rear fenders, along with the number plate, side
cover and front fork protector have been redesigned for an
aggressive look. Less plastic is used to expose and enhance the
lightweight aluminum frame.

Key Features

1
YZ450F’s new rearward-slanted cylinder is a revolutionary
advancement that achieves unmatched mass
centralization, concentrating inertial mass toward
the center of the machine. This bold new design
also swaps traditional intake and exhaust positions,
putting the lightweight airbox and throttle body
out front. This contributes to mass centralization
for nimble handling while also achieving a straight
intake tract for superb combustion efficiency that
delivers more power.
2
The cylinder is offset so the connecting rod is
vertical at the moment of greatest combustion force,
minimizing piston friction against the cylinder wall
that could rob power. That means quicker response.
3
The new 4-titanium valve cylinder head is matched
to a fuel injection system developed specifically for
the YZ450F. Instantly adapts to changing air/fuel
mixtures depending on altitude and temperature, for
an engine that delivers no matter what conditions.
4
The all-new aluminum Bilateral Beam frame
provides a superb rigidity balance that complements
the engine for unmatched lightweight handling and
cornering. The result? The best cornering, most
nimble 450F for all track conditions.
5
Revamped looks deliver new-generation styling,
including front and rear fenders, intake cover, front
fork protector, and number plate, along with the fuel
tank and seat.
6
Accessory GYTR® Power Tuner lets bike tuners
adjust air/fuel mixture and ignition timing maps to
match engine performance characteristics to the
rider and track conditions.