Yamaha YFZ450R

Topping last season’s all-conquering YFZ450 was always going to be a challenge. The new 2009 YFZ450R successfully steps up to Sports ATV pole position by moulding totally uncompromising engineering into instant race-winning potential.

The YFZ450R story starts with a new, massively rigid but very lightweight cast aluminium and steel hybrid chassis. Though the footprint is wider and the suspension longer than the YFZ450’s, the YFZ450R is physically shorter overall than its predecessor, giving it a more agile, nimble feel.

Sitting low in this chassis is a 449cc 5-valve DOHC liquid-cooled engine with reshaped intake ports and fuel injection controlled by a 32-bit ECU.

The engine’s dry-sump design allows for a shallower crankcase, lowering the centre of gravity still further for even sharper handling. Pressure lubrication from a separate (small) drysump tank inside the crankcase reduces weight and rules out oil starvation under high G-forces.

The intake port design and valve timing have both been modified for increased low and midrange power. A new exhaust boosts low and midrange power, while a new five-speed gearbox with taller ratios drives through an up-rated clutch. The result is an ATV packing linear, muscular acceleration.

Increased wheel travel and longer suspension arms maximise the YFZ450R’s performance potential without compromising overall balance, handling or agility. New tread-pattern tyres make turn-in even sharper and a lightweight 220mm ‘wave’ disc reduces unsprung weight. Ideal riding ergonomics are made possible by a four-setting handlebar adjustment system, a new throttle lever, remodelled seat and wider footrests.

Current Australian #1 plate holder Ryan Lancaster will upgrade his all conquering YFZ450 to the new YFZ450R for 2009, competiition watch out!

KEY FEATURES

In ATV motocross, great power output doesn’t mean much without superior handling.

YFZ450R delivers! 75mm wider overall than the YFZ450, the stance of this new 450R is motocross-ready. The frame is designed of lightweight aluminium, with a tension-steel bottom frame that lets the engine sit lower for excellent mass centralisation. Suspension components have more travel carefully chosen for best performance, and the front shock bodies feature Kashima coating for even smoother operation.

Fatigue can sometimes be a racer’s worst competition. That’s why the YFZ450R’s designers made this ATV so comfortable.

It’s much roomier, with plenty of room to hang off in the corners, and the seat is padded just right to be more comfortable regardless of riding position.

Handlebars are 4-position adjustable, too, so every rider can choose the best position, and the throttle has been designed for all day comfort. What’s more, the engine balancer has been revised to even further reduce vibration.

This 449cc engine uses the cylinder head and cylinder from the championship-winning YZ450 for awesome power output. That means titanium five-valve cylinder head technology, with a camshaft designed just for this machine to deliver abundant low to midrange torque for performance where you can really use it to take the lead – while still maintaining a super strong top end to let you pull away from the pack.

The YFZ450R adopts fuel injection for precise fuel delivery. With big 42mm Mikuni throttle body and 12-hole injector, this system provides exceptional fuel atomisation for maximum power. The system also includes ISC (Idle Speed Control) for easy, reliable start-up and warming.

This ATV is designed to make race prep easy. Body panels come off easily for service; there’s no need to remove the battery or other components to get the fenders off.

The aluminium frame is bolted together, rather than welded, for maximum durability. And the oil tank is integrated with the crankcase so it’s easier to service the engine.

ENGINE

Power deliver is smooth and strong off the line with lots of low and mid range where you need it. As rpm climbs you’ll find the same top end punch that has made the YFZ450 such a fierce competitor and class leader.

The new crankcase holds the newly designed crankshaft that’s ready to handle the increased torque output, as well as the counterbalancer that has an increased ratio for superior vibration control. The crankcase also houses the oil tank, which helps to centralise mass for unmatched handling and makes maintenance easier.

Camshafts are all new for this model, and are designed to maximize the torque available in the low and mid ranges.

Fuel injection uses a 12-hole injector that provides exceptional atomisation of the fuel for maximum combustion efficiency and power delivery. The system also uses a big, 42mm Mikuni throttle body and includes ISC (Idle Speed Control) for easy, reliable startup and warming.

CHASSIS

Spacious ergonomics allow room for an aggressive racer to move around during the moto, and the ATV’s body panels that the rider contacts during operation are of a special, softer plastic material for greater comfort. And the seat is narrow in the front, yet wide and padded in the rear to provide a more comfortable ride, even when hanging off on the side of the seat in a turn.

Wheels are set motocross-spec wide, near the maximum allowable 1270mm, for great cornering ability.

The newly designed Dunlop front tyres have a superb combination of the right compound, tyre profile, tread pattern, and sidewall-totread- centre-stiffness ratio to provide outstanding comfort, bump absorption, and precise cornering performance. The rear Dunlop tyres also help the rider achieve a high level of performance with superb feedback in turns and great grip on the turn exit. At 20 inches rear and 21 inches front, the tyres also provide much better ground clearance than the competition. That makes the YFZ450R fun to ride off-road, too.

ProTaper handlebars are mounted on four-way clamps for exceptional adjustability. There are two sets of holes in the handlebar crown, and eccentric clamps so the rider can choose the standard setting, 10mm or 20mm forward, or 10mm back.

Foot pegs are a huge 65mm wide, something riders will appreciate every time they want to get up on the pegs, with good kick-up on the ends for solid footing.

The all-new frame is aluminium for lightweight, except for the frame member under the engine. Here tensioned steel is used for its combination of strength and thinness. This allowed the designers to sit the engine lower overall for excellent mass centralisation for unmatched handling.

The front frame is noticeably narrow at the A-arm mounting points.

This dramatically reduces changes in camber as the long A-arms travel through their full range of motion. The front 44mm KYB shocks have Kashima coating for smooth operation with superb bump absorption and excellent anti-bottoming characteristics. The 250mm of wheel travel means this racer is up to even the most challenging tracks.

The rear swingarm is crafted of strong, gravity-fed aluminum, and it’s matched to a fully adjustable 46mm KYB piggyback shock absorber for excellent handling. Rear wheel travel is 280mm for comfort even on tough terrain.

For excellent stopping ability, YFZ450R features dual front hydraulic disc brakes and a trick looking, lightweight wave-type rear rotor.

OTHER

The new throttle lever requires less effort, and it’s very comfortable to use. That means less fatigue during all-day riding.

The instrumentation is all business. The discrete panel on the fender in front of the rider gives vital indicators about low fuel, coolant temperature, check engine, and neutral gear via a straightforward LED display