Yamaha WR 450F

The WR450F was already a proven leader in the big-bore off-road world, but for 2006, we decided to bump up the Nasty-Meter.

A lower overall frame and seat height means that it's easier to get down and dirty on your favourite trail. Slimmer rad shrouds, seat and fuel tank mean that you've got more room to manouver - if you can catch your breath. Larger, fully-adjustable 48mm fork and lighter Renthal aluminum handlebars give you precise control of this trail taming beast. Once you fire up the 5-valve 4-stroke with the touch of the reliable electric starter, you'll notice that we've also added carb and ignition settings. The perfect bike just upped the ante.

Engine:

Liquid-cooled, 449cc, 5-valve, DOHC, 4-stroke powerplant with super light titanium valves. The long-stroke engine design delivers broad, flat power characteristics with crisp, linear throttle response tuned specially for serious off-road use.

Ultra-convenient electric starting means fast, sure starts. The electric starter is also backed up by a manual kickstarter.

Automatic decompression system ensures fast restarts in any gear.

Convenient, handlebar-mounted hot start lever for easy restarts when the engine is hot.

Compact cylinder head design and magnesium cylinder head cover help reduce weight.

Optimized combustion chamber design provides the most efficient intake and exhaust flow for maximum engine performance

Titanium valves and load-reduced springs decrease weight by more than 40% over a conventional valve train and reduce reciprocating mass for faster-revving, smoother-hitting power delivery across the rev range.

Special cylinder design features cutaways that allow the air trapped under the piston to enter a side chamber (or cutaway) to reduce horsepower-robbing "pumping losses."

Lightweight crankcase also utilizes cutaways to reduce "pumping losses." The crankcase cutaways match the cutaways in the cylinder.

Lightweight crankshaft decreases inertial mass for fast, low-rpm throttle response.

Lightweight, short-skirt, forged piston for great durability

Compact design automatic cam chain tensioner reduces maintenance and mechanical engine noise.

39mm, Keihin FCR, flat-slide carburetor with throttle position sensor (TPS) ensures ultra-precise fuel/air mixing and lightning-quick throttle response. The fuel spigot is a moveable joint for easy serviceability.

CD ignition system delivers a more precise spark and monitors engine speed to ensure optimal timing for strong, fast engine response.

Lightweight direct ignition coil is integrated into the plug cap to reduce weight and complexity

Slick-shifting, wide-ratio, 5-speed transmission is geared specially for smooth-hitting power in the woods and hard-pulling top-end on open trails.

Heavy-duty clutch matches engine output and offers a light, progressive clutch feel with less lever effort for smoother shifting.

Quick-access, lightweight magnesium outer clutch cover allows fast, easy access to the clutch.

Larger-capacity, dual radiators with special air directing louvers ensure maximum cooling efficiency.

Washable, dual-stage, foam air filter features tools-free to access to the airbox and filter.

Revised header pipe features a specially shaped header angle maximizes engine power and allows hassle-free replacement of the oil filter. The header pipe is made of stainless steel and features a heat shield. This system maximizes engine power and allows hassle-free replacement of the oil filter.

Lightweight aluminum wrapped muffler optimizes both power delivery and appearance. This muffler design features a "serviceable", screen-type spark arrestor which prevents sparks from exiting the exhaust. Its repackable design means you can maintain optimal engine performance and reduce noise levels.

Trick, works-style clutch lever features an oversize "barrel adjuster" for easy, on-the-fly adjustability of lever/cable play. There is a new, larger boot covering the adjuster that provides more grip for easier operation.

SUSPENSION:

Super-strong, semi-double-cradle frame reduces weight and provides great lateral rigidity for minimal flex and razor-sharp handling.

Removable, aluminum, rear sub frame constructed of square-section pipe reduces weight and provides easy rear suspension access. For 2005, new conventional hex head bolts have replaced the Allen-style bolts that secure the sub frame to the main frame for easier, faster servicing.

New, lightweight, tapered, aluminum swingarm is produced using "hydro forming", a special forming method that uses high pressure water to form shapes. The new swingarm provides improved overall chassis balance thanks to the addition of re-enforcing ribs in the cast aluminum around the pivot area. The result is a 2% increase in torsional rigidity for improved handling.

Revised 48mm, adjustable, inverted Kayaba cartridge fork provide excellent suspension performance. The outer (male) tube is changed to optimize rigidity and is Kashima coated to reduce friction.(changed from Alumite) . The center rod size has been reduced form 8mm to 6mm while the cylinder diameter has been increased from 25 to 28mm. This new fork no only offers excellent suspension function but also reduces weight too.

A new oil lock system in the new fork is now utilized. This new oil lock system enhances suspension performance and improves rider comfort.

The 48mm fork utilizes a Transfer Control Valve (TCV) which enhances the damping force from mid stroke to full stroke and improves bottoming characteristics. The benefit of TCV is more precise control throughout the full stroke range.

Front wheel travel is 300mm (11.8"). Front fork adjustments include: 20-way compression damping and 20-way rebound damping. Optional fork springs are available through Genuine Yamaha parts.

New larger plastic fork protectors wrap further around the fork tubes for increased protection. They are self-supporting design to reduce friction for smoother fork operation. The routing of the wiring for the new electric speed sensor (no longer a traditional cable) now passes on the inside of the fork leg protector for added protection.

Revised upper and lower triple clamp feature a new painted mat titanium finish for an improved appearance.

New adjustable handlebar mounts on the top triple clamp allow the handlebars to be moved 10mm rearward if desired.

Lightweight, Renthal aluminum handlebar with reinforcing crossbar and foam pad

Monocross rear suspension system features a revised, fully adjustable, Kayaba shock. This new shock now features a dark gold coloured shock body and new revised settings for improved rider comfort and handling. Shock adjustments include; spring preload, 20 clicks of low speed compression damping, 2 turns of high-speed compression damping and 20 clicks of rebound damping. Rear wheel travel is 305mm (12").

250mm, fully floating front disc brake with twin piston caliper fitted with lightweight aluminum pistons provides excellent braking performance. Revised shorty style adjustable front brake lever offers improved hand comfort and grip.

Revised 245mm rear disc brake utilizes a new single piston caliper. The caliper is mounted lower on the swingarm to add additional clearance for the exhaust pipe. The rear master cylinder is integrated with the fluid reservoir to reduce weight. This revised set-up delivers strong, progressive stopping power with excellent control and feel.

All new multifunction digital meter assembly. This compact meter features 2 modes. The first is the "basic" mode and features: speedometer, odometer, resettable dual tripmeters, and a clock. The second is the race mode and it features speed, an automatic start timer, and the ability to edit the tripmeters and an odometer.

New, lightweight, rugged Excel 21" front and 18" rear rims provide exceptional durability and help reduce unsprung weight for optimal suspension performance.

New design front fender and seat. The seat base and foam has been revised for more cushioning effect and improved rider comfort.

Sun Star specially designed rear sprocket increases the contact area between the sprocket and chain rollers, thereby reducing the load on the chain and increasing service life of both chain and sprocket.

The regulator has been re-located to the steering head area.

Features:

Premium Dunlop knobbies offer great traction and excellent wear.

"Slim line" bodywork is very similar to the YZ bodywork. The fuel tank capacity is 8 liters . The "slim line" body allows fast, easy rider movements and a lighter overall machine feel.

Enduro-style lighting front and rear increase versatility by maximizing nighttime and low-light visibility.

On-off-reserve fuel petcock provides peace of mind.

Wide, serrated, folding, cast alloy footpegs provide excellent grip.

Serrated rear brake lever and folding shift lever tip offer superb grip and excellent durability.

Specially designed, detachable, lightweight, aluminum kickstand folds well out of the way and allows lots of Ground Clearance.

Inner clutch cable is stainless steel for longer life.

Rugged engine and water pump protector plates

All new lighter plastic, lower rear disc protector

Newly designed rear caliper protector

Low-maintenance, sealed, gel-type battery

Waterproof starter button and engine kill switch are handlebar-mounted

Handy lifting holes in the side covers

Yamaha bunged on a great ride in Australia's alpine country to introduce its new electric-start duo - the WR450F and WR250F. Barry Ashenhurst was there to take it all in.

Everything Yamaha does these days seems to push it another notch above the opposition. It seems to advertise more than anyone else. It has a PR machine that actually functions - a miracle in an industry in which the discipline is largely ignored - and in some states, Queensland for example, it seems to be involved one way or another in everything but soup kitchens. Yamaha has a very public face. It's a face all dirt riders recognise, and that's what you call good marketing.

The company also knows how to get that face in the press. Anyone who rides a dirt bike, Yamaha or otherwise, has watched with interest as the evolution of the WR-F and YZ-F series four-strokes unfolded. Much of the sustained interest was due to Yamaha's strategy of teasing us with tidbits of information long before the new bikes arrived - and then coming up with a winner.

Honda made us wait years for an electric-start four-stroke and then gave us a school bus called the XR650L. Yamaha built expectations with tantalising delicacy, then treated us to the WR400F, a bike you could race or trail ride without major modifications and that, unlike the XR650L, actually weighed less than a fully optioned armoured car.

We were mesmerised by the YZ400F and WR400F, and thought they were some sort of miracle when they were released in 1998, though in truth, Yamaha was building on short-stroke, high-revving engine characteristics pioneered by manufacturers like Husaberg. What Yamaha did that marques like Husaberg didn't do was put its engine in a much better engineered, and dare we say a much more reliable package. That made it a much better bike.

The WR400F enduro model went on to become a best seller before turning into the WR426F. Now that beast has turned into the $11,599 WR450F - the first electric-start WR - introduced to the motorcycling press alongside the WR250F (also with an electric leg) at a press function in the New South Wales high country recently. As an introduction to a new model, it couldn't have been better.

It became obvious right away that a great deal of effort has been expended in making these new bikes lighter: the word "lightweight" pops up frequently in Yamaha's press material. So does the word "new". In raising the engine displacement of the biggest WR to 449cc, Yamaha has also taken the opportunity to refine some of the bike's characteristics and make improvements where they were needed, to the extent that the 450 is actually a new bike.

In changing or updating virtually everything, Yamaha also revamped the power delivery, and frankly, we think that's good news. The WR426F had an aggressive engine and a slab of midrange-hit that some riders, me included, just couldn't handle. Like the motocrosser, the WR426 was a bike you could either ride or you couldn't. It was as if Yamaha had said: "Yeah, we can make a four-stroke behave like a two-stroke, watch this", and built the 426 to prove it.

ANYONE CAN RIDE IT
You could say the same thing about the WR450 versus the WR426 and have few riders disagree with you. For all the improvements to the new bike, and the increased power, the first thing I noticed about the WR450F was how unintimidating it is. The bike is fast enough for most of us, but it's not scary. Anyone can ride this bike and enjoy it, and it seems to me that that's a deliberate move on Yamaha's part. Having proven it can build a four-stroke that behaves like a two-stroke - a considerable achievement - it's now offering us a 450cc four-stroke that's easier to ride than its 250cc four-stroke; an accomplishment even more worthy of our admiration.

The 450 engine is very strong, but there's no vicious power snap to freeze your sperm into a million quivering shards. The energy is delivered in what bike scribblers like to call a "linear" fashion - in other words, proceeding in a straight line with no bumps or sphincter-spasms in the power curve.

The WR450F is an easy, fast, bike to ride: it's greatest virtue. In my opinion, enduro riders will want a performance pipe to encourage faster throttle response, stiffer suspension at both ends if they're big blokes, and more aggressive knobbies than the street-legal Michelins that are on there now, but for most trail riders this bike is set-up very well.

The ride is plush; the suspension is more progressive than it was on the earlier WR400 or the WR426; there's plenty of power on tap; the bike exhibits neutral handling at trail speeds; it steers well; it doesn't pull any dirty tricks on you; and has very nice brakes.

I had some difficulty finding neutral on both bikes. That may be a gremlin that inhabits only pre-production models; then again, maybe it isn't.

 You don't have to be an expert to ride the 450; most blokes will ride it all day and get home without the distraction of liquefied kidneys and permanent sphincter pucker. Having so much power available, in a bike that seems to get so much of that power to the ground without wheelspin, is a big advantage, and we reckon the 14-50 gearing is damn near perfect for trail riding.

I don't know how many dirt riders would consider both these bikes before buying one of them, but I have to say that I thought the 450 was easier to ride than the 250, and to be honest, was a lot more fun. I thought the 250 was set-up slightly firmer than the 450, but you don't have to rev the bigger bike as hard, and there's more margin for error in gear selection.

Frankly, while saluting the masterful engineering that produces so much power in such a small engine, the 250 is just too much hard work for me.

On the other hand, the smaller bike would certainly have an advantage in terrain where you have to change direction quickly and constantly.

If I had to choose between the 450 and the 250 ($10,999), I'd buy the bigger bike, simply because offers more power in the same-size package, and therefore requires less physical effort for the same result.

Source Bike Point