Yamaha YZ250F 2001

Four strokes to glory?

(From the pages of Australian Motorcycle News, by Mark Fattore.)

Yamaha's new YZ250F four-stroke motocrosser is a bit like one of those zany roadside attractions - the Big Pineapple for instance - you see on the edge of a boring stretch of highway anywhere in Australia. Because there's nothing else within cooee of them, and people are longing for some sort of visual stimulation, these wacky institutions tend to monopolise interest, and in turn, the tourist dollar - and bravo to them. After all, there's something to be said about pre-empting everyone else and reaping the rewards.

That's the appealing situation that Yamaha is now in with its new motocrosser - it's all alone in the world of competition-bred 250cc four-strokes. And this bike is no gimmick; it's the real deal, and the first volume-production machine of its kind.

FOLLOW SUIT
Since Yamaha first unveiled its YZ400F four-stroke machine in 1997 - which went on to clinch the 1999 World 500cc Motocross Championship under the whip of Italian dynamo Andrea Bartolini - it's almost been a given that the Japanese marque would follow suit with a scaled-down version. So it was no great revelation when the first official photos of the YZ250F did the rounds of the international bike mags in June. The writing was on the wall.

This machine promised so much on paper all those months ago - after all, dry weight was claimed to come in at 96.5kg, which is 1kg less than the marque's equivalent two-stroke YZ250. That's on top of the promised performance bonanza - although official horsepower and torque figures still haven't been made public by Yamaha. However, believe me - the liquid-cooled YZ250F does justice to the paper declarations. It's that good.

CONSIDER THIS
But why a 250cc four-stroke in the first place? Well, for a start, there is a competition outlet for the machine, which will be eligible to race in national AMA 125cc motocross and supercross events in 2001. That rule is set to be adopted in Australia a year later.

The AMA ruling is really no great surprise, as the organisation had already paved the way for big four-strokes to compete in US 250cc nationals in 2000 - which they did, with limited success.

Meanwhile, in Australia, not only will the YZ250F be eligible to compete in 125cc motocross events from 2001, but there's also the Pro-250cc class in the Thumper Nationals to consider, and let's not forget that recreation registration is another option for the dedicated trailbike rider, although the new WR250F will probably steal some thunder in that area.

So, Yamaha certainly won't be short on marketing channels when the YZ250F goes on sale next month (price is yet to be confirmed, but don't expect much change out of $10K).

NO GREAT SURPRISES
As the YZ250F was wheeled out of the huge CDR/Yamaha transporter at the Breakwater motocross track in Geelong (Vic) - the headquarters of the Craig Dack-managed factory race team - it was immediately obvious to the naked eye that the bike looks strikingly similar to the YZ426F. That's no great surprise, considering they share the same rear suspension, rear frame, swingarm, two-tone seat and brakes. But that's not the end of the F's graft and corruption.

It's also pinched its plastics from the YZ250 two-stroke, and just to complete the team effort, there's even a few bits of the YZ125. Yes, there's something to be said for family ties - and stretching out economies of scale as far as possible.

The YZ250F that I sampled is one of three pre-production models that are currently housed in Australia. And it'll probably be the last time it's touched by a journo, as after the test it was tarted up for its competition debut at this weekend's (November 25-26) final rounds of the Supercross Masters at the Sydney Superdome (it'll be competing in special four-stroke events, with Chad Reed aboard).

Just on that score, I've never been one for bold predictions, but I think this bike will make one heck of a supercross mount, especially against the 125cc strokers. Time will tell.

RESPECTABLE DEMEANOUR
It only took me a few circuits of the sodden Breakwater track to realise the potential of the YZ250F. The engine is very responsive, but not in a way that you're struggling to keep the whole plot tracking in a respectable manner. It doesn't actually feel too four-strokish when you're on the boil, as engine braking is minimal and it feels incredibly light.

Like the YZ426F, the engine is a five-valve, DOHC configuration, with a bore and stroke of 77mm x 53.6mm and a single counterbalancer. The whole lot is fed via a 37mm carburettor.

It's that short stroke which helps it to build revs quite quickly - aided by the absence of any excess weight - all the way through to the 13,500rpm 'redline'.

I must confess that I didn't take advantage of the bike's powerful top end during my first 30-minute foray, as it's easy to fall into the 'torque curve' trap and let the bike pull you along. That's the trailbike side of the machine, but crank your riding up another level and it'll certainly accommodate your needs.

The gearbox is well mated to the free-spinning engine, with the ratios quite close together. However, top gear (fifth) is quite tall, and first is quite low, but in between it's a good compromise.

The cable-actuated clutch is fuss-free, although in a couple of dummy starts in second gear I found it quite a task to produce a clean getaway. Probably a technique thing, but if there's one thing you need in a supercross race it's a solid gate.

The bike comes with a manual decompression lever, which I guess is a necessity for a competition-bred four-stroke - get caught out kicking your butt off after a bingle and you'll soon be suffering meltdown. Not to mention a DNF next to your name.

The decompressor is complemented with a special carburettor-mounted 'hot start' lever, which ensures that the whole shebang fires into life on cue - just as the long as the original starting instructions are on the mark...

Inverted 43mm Kayaba forks grace the YZ250F, adjustable for rebound at the top of the fork leg and compression at the bottom. Still endowed with the standard factory settings, they were fuss-free, although the rear YZ426F-based rear suspension was a little soft.

However, at the base level the YZ250F handles superbly - instead of the rider questioning the bike, it's more like the other way around. That's not an exaggeration, as you can really push it to the envelope without feeling that you're on the cusp of doom.

The standard Dunlop 739-series tyres help out here, as they were excellent at Breakwater.

Wheelbase comes in at 1475mm, which is in the YZ125-type ballpark. That's another reason why this bike is going to give all 125cc motocrossers a fright - it handles just as well, and will drive out of a turn just as competently.

REAP THE REWARDS
What Yamaha has achieved with the YZ250F is not revolutionary - after all, it's pretty much a template of big brother and there are a number of four-strokes already on the market. But, in the true sense of the word, most really are trailbikes compared to this jigger. This is an out and out racer, and with what I've sampled it just may enliven many a motocross track around the globe. Yamaha's signalled its intentions - and it just may reap the rewards.