2015 Yamaha YZ450F

Berm Warfare

Words: Callum Pics: Paul

In whatever form it takes – for moto, enduro or cross-country – Yamaha’s 250F is a hit with everyone, but what about its bigger brother?

When it comes to innovation in motorcycles, both on and off road, Yamaha holds the honour of always being one to think outside the box and pushing forward – or backwards as might be the case – with new feats of engineering.
When the first of the reverse engines was unveiled in 2009, it was unlike anything the motocross industry had seen; but despite all that hyperbole of being “the future”, the YZ450F quickly became a much-maligned motorcycle. Whether it was the flighty feeling up the front end, the raw power that was hard to keep in check or the dubious honour of being the bike that saw James Stewart take many tumbles on, Yamaha’s flagship dirt bike was not living up to its hype.
Like all innovators, the first year of new technology is rarely ever perfect, which has been the case for almost every aspect of a modern motocross bike.
The first aluminum frame on a motocross bike was a rigid roach that put most riders off, but it soon became the status quo for four out of five major manufacturers. The first Japanese four-stroke, which was the basis for all that came after – and one that this very bike is a direct descendant of – was notorious for having enough engine braking to throw a rider, being impossible to start when hot and, well, being impossible to start when hot.
Still, no amount of positive spin from the Japanese marque, or good press and race wins could stop the YZ450F being declared an ill-handling machine that throws riders.
Fast forward four years, when the next generation of 450 was released, and it was a completely different story.
The Yamaha YZ450F only came into its own in 2014, when the engineers made some small yet pivotal changes.
How much of a difference did it make?
It went from being considered a dog – albeit, one with plenty of horsepower – to being an outright contender for Bike of the Year.
In fact, it was neck and neck with the reigning titleholder that was the Kawasaki KX450F.

FULL POWER TRIP

The engine that we got in 2010 was never low on horsepower. In fact, if it could claim any title, it would be for power. But it was ruthless, making aspirated big-bore two-strokes of the Eighties seem like nothing. That’s why Yamaha’s first task was to make the power more usable.
Face it, despite all the ruts, trails and ales that you and your friends partake in and then bench race about, a four-fifty is more power than any mere mortal – and most professional racers – will ever need on the track.
But ego, a good sales pitch and that bark of a motocross big-bore means that more MX1 machines are sold than its MX2 brother.
While it was more to do with good press than being politically correct, Yamaha thought to tame that power in 2014 to be less abrupt.
Why did they do that?
Before they did, even during the most passive of turns, riders with even the best of throttle control could sometimes find the front wheel pointing to the sky – this writer included – and that didn’t always end well. The current generation is nothing like that, with a low end that comes on smooth, meaning riders who do not sit in the higher revs can make the most of the engine.
But that’s not to say it doesn’t have top-end, ‘cause it does – and in spades.
Sure, there are racers out there (and a lot of weekend warriors that hit the trails) who are adamant that they love that particular raw hit of power. Trust us, even the “mellower” – mellow being something that is rarely mentioned when writing about MX1 motos – can still do the damage you so want.
The delivery of that claimed 55 ponies can be adjusted to suit, due to another innovation by Yamaha Motor Company, which is the Power Tuner. The handheld interface, which plugs into the YZ allows fuel injection and ignition mapping to be tuned, isn’t included with any of the YZ-F range.

AIR FORKS?

While the reverse-mounted engine and the overall handling took a beating from riders and press, there was one area – and one that always plays a big part in the handling of a bike – that it hit out of the park: the suspension.
The 2015 YZ450F still has the same formula for its springers, too, with the Kayaba SSS forks.
So, even the innovator that Yamaha is, the range of YZs don’t come with air forks?
No.
Sure, air forks costs less to produce and are, in theory, easier to adjust on the go, along with being almost a kilo lighter than an oil and spring fork.
But Yamaha still used the tried and true Speed Sensitive Suspension.
You can be thankful that they did, too, since the suspension package on the Yamaha is considered the best that is currently available.
Will Yamaha stick with Speed Sensitive Suspension on the 2016 motocrossers?
Time will tell.
But given how stubborn the Tuning Fork was when it came to its reverse engine ideal, it would not be surprising if the manufacturer bucked the trend of air forks and stuck with moving oil and springs.

2015… THE FUTURE

Okay, now you know the big changes that took the YZ450 from that original bike in 2010 to what we now have, due to the major changes in 2014 – the latter being a totally new bike.
So, what’s new for 2015?
There is a host of updates, that include the mundane – being different fasteners to secure the airbox cover – to the details that always make a difference – such as the valving on the forks and different mapping on the ECU.
But it is those details that help make the complete package.
We’ve spoken off the Kayaba SSS forks, which have had changes to make them better than previous versions, but it is also the details such as the finish that aids in making the bike one of the best four-fifty motocross bikes on offer. Like all Yamahas, the quality of the motocrosser is better than most, seeing the smallest detail taken gear: such as the aforementioned dzus fasteners on the airbox cover, to clean welds and quality components like ProTaper ‘bars and black anodised Excel rims.
Yes, it might be contrary to have a state of the art engine setup mated to what is considered ‘old’ technology, but replace ‘old’ with ‘proven’ and you have a bike that is up to the challenge of sticking it to other bikes and keeping up with the Joneses.

2015 YAMAHA YZ450F

Standard: $13,799
Special Edition: $13,899

Engine Type: 449.7cc liquid-cooled DOHC four-stroke; four titanium valves
Bore x Stroke: 97.0mm x 60.8mm
Compression Ratio: 12.5:1
Fuel Delivery: Yamaha Fuel Injection (YFI) Keihin® 44mm

RUNNING GEAR

Transmission: Constant-mesh six-speed; multiplate wet clutch
Front Suspension: KYB Speed-Sensitive System, inverted fork: fully adjustable, with 315mm of travel
Rear Suspension: Fully adjustable single shock with 315mm of travel
Front Brake: Hydraulic single disc brake with 250mm rotor
Rear Brake: Hydraulic single disc brake with 245mm rotor
Front Tyre: 80/100-21 Bridgestone M404-A
Rear Tyre: 100/90-18 Bridgestone M403

Dimensions

Length: 2165mm
Width: 825mm
Height: 128mm
Seat Height: 966mm
Wheelbase: 1475mm
Ground Clearance: 325mm
Fuel Capacity: 7.5L
Wet Weight: 111kg

BACK TO THE FUTURE

Do you remember the first time you saw the future? Cast your thoughts back to 2009 when we were first made privy to the 2010 YZ450F and its groundbreaking back-to-front engine. Like me, you might remember thinking it looked liked something out of Star Wars. The radical engine design made it so very different to everything we’d seen before, which is the reason why most of us were asking the same question: was this really the future?
Here’s what we thought…

“There is no doubt that under power is where this bike shines. It feels light as you sit in the power. You would never notice the extra three kilos the YZ gained when it took on fuel injection – until you get off the throttle, that is. This is when you notice the build of this big brother, along with the wide radiator shrouds that came with the new position of the airbox. It is definitely not in the lightweight division, nor is it the easiest bike to throw into corners or stop suddenly on.”