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YZ450F: The theory of revolution

When an existing design approaches its limits, it’s time to call in the revolutionary thinkers. The creative minds who aren’t afraid to throw everything out and start from scratch.

Which is exactly what happened with the latest incarnation of our championship dominating MX bike. Accepted wisdom has been turned on its head to produce our most effective motocross bike yet. Meet the revolutionary new 2010 YZ450F.

The 2009 450F captured back-to-back World and Aussie MX titles as well as the World and AMA SX crown, so the challenge to take the open class weapon to the next level was a big risk. Because to reach that level, a new approach was needed.

The solution looks simple, but the decision was bold… take mass centralisation in a new direction by fitting a rearward facing and backward tilted cylinder. Now the heaviest part of the bike is closer to the middle… right where it needs to be for amazing levels of flickability.

But theory is nothing without practice to back it up, so Yamaha testers nailed berms, scrubbed jumps and blitzed straights lap after lap to fine tune the new design, to confirm the agility of the new bilateral beam frame, the linear power delivery offered by the sweet fuel injection system and awesome punch from the high torque four-valve motor.

It’s not change for change’s sake. It’s the lightest handling, whoop-skimming YZ450F yet.

2010 YZ450F Features:
* YZ450F’s new rearward-slanted cylinder is a revolutionary advancement that achieves unmatched mass centralisation, concentrating inertial mass toward the centre 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 centralisation 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, minimising piston friction against the cylinder wall that could rob power. That means quicker response.
* 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.
* The all-new aluminium 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.
* 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.
* 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.
* Air filter case is changed to accommodate new engine layout. Putting it up front keeps dirt and dust kicked up from the rear tyre 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.
* Aluminium Bilateral Beam frame is crafted from a carefully chosen combination of forged and extruded aluminium, 16 components in all, for the right rigidity balance and light weight.
* New skid plate is constructed from tough polypropylene for great protection and low weight.
* 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 optimised combination delivers exceptionally linear performance for excellent bump absorption and awesome cornering ability.
* 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 centralised 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.
* Triple clamps are redesigned, with a change in offset from 25 to 22 mm for unequalled cornering performance. ProTaper bars are four-way adjustable to accommodate a wide range of riders.
* 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 aluminium frame.
* Fuel pump is small and lightweight, as is the compact transistor ignition unit.