First look - 2011 Yamaha YZ450F
19 Oct: In the USA the 2010 YZ450F garnered the reputable title of Dirt Rider Magazine’s “Bike of the Year.” Not to mention Cycle World’s “Best Motocrosser” and Motorcycle Magazine’s “Best Dirtbike of 2010.” Here is their 2011.
Copy and photos courtesy of Yamaha USA.
- YZ450F’s rearward-slanted cylinder is a revolutionary advancement that achieves unmatched mass centralization, concentrating inertial mass toward the center of the machine. This bold 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.
- 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.
- The 4-titanium valve cylinder head is matched to a fuel injection system developed specifi cally for the YZ450F. Instantly adapts to changing air/fuel mixtures depending on altitude and temperature, for an engine that delivers no matter what conditions.
- The 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.
- 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.
- 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.
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- New clutch lever and pushrod for more consistent clutch feel during long motos.
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- 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 engine layout. Putting it up front keeps dirt and dust kicked up from the rear tire away from the intake system.
- "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 designed to give the rider great shifting feel.
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- 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.
- 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 excellent feel and shock absorption.
- KYB® rear shock with large capacity piggy back reservoir and 50mm piston for more consistent damping control.
- Fuel tank is positioned underneath the seat, contributing to the centralized mass. The seat is long and flat for to allow free rider movement.
- Rear sprocket shape has a trick appearance and is light weight.
- The triple clamps are designed, 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 designed for an aggressive look. A minimalistic design is used to accentuate the handling character of the bike. Less plastic is used to expose and enhance the lightweight aluminum frame.
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- Fuel pump is small and lightweight, as is the compact transistor ignition unit.
- USA riders have a choice of two color options: Team Yamaha Blue and White or White and Red.
Comment: A 'first ride impression' by Doug Dubach is posted on VitalMX:
A little curious in that the video intro by Tim Olson is hijacked by a KX450 advert !!
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