2008 Yamaha MX-ers have a beast within

Published Oct 22, 2007

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Yamaha makes no bones about it - these are the only bikes in its range designed solely for racing; comfort, cost and fuel efficiency are all secondary to their primary purpose of going around a motocross course faster than similar bikes made by other manufacturers.

Add to that the fact that I'd never before ridden a motocross bike and had never even seen the Springfield off-road circuit in Durban and you'll understand I was a little intimidated when Yamaha SA invited me to ride its 2008 motocross machines, including its flagship YZ250F and YZ450F four-stroke flagships.

Well, I needn't have been; off-road racing is more about control than anything else and, radically powerful as these machines are, they're also incredibly accurately controllable - which doesn't necessarily make them easy to ride.

Neither bike is all new for 2008 but Yamaha has made a number of detail changes to the engines (for more power) and the chassis (for better control).

On the advice of Yamaha's Peter Corkin I rode the YZ250F first; it looked intimidatingly high but settled on its suspension when I put my (not inconsiderable) weight in the saddle and I could put both feet on the ground.

The engine started easily from cold on the choke but took some time to warm up; hot-starting (as in when you stall it) requires a totally different procedure (you hang on to a little trigger above the clutch lever as you kick the engine over) but it's no longer the foot-breaking impossibility it used to be.

The clutch was surprisingly heavy, with a sudden and very solid hook-up, the gearshift rather notchy but very positive with a very short lever throw but the initial impression as I moved out onto the fast and very technical Springfield circuit was of the incredibly violent, but at the same time precisely accurately controllable, engine response.

The YZ250F has a humungous Keihin FCR-MX37 carburettor, dual cams, five valves and no flywheel effect to speak of. Throttle response is practically instantaneous and the revs rise and fall incredibly quickly, which makes it easy to dial in just enough once you teach your right hand just how sensitive the twistgrip is.

Most of the running-gear upgrades for 2008 focus on making the bike turn in more quickly and improving its braking; it has new triple clamps and upgraded suspension units at both ends, making the steering very quick indeed.

The bike wasn't as stable as I expected but turns in astonishingly quickly for a machine with a 1469mm wheelbase and a 21" front rim, which of course is more important for racing.

Springfield's MX circuit has a lot of steep jumps and difficult transitions; I found I was concentrating more on learning the circuit than on exploring the bike so switched to the "enduro loop" a fast, relatively flat ,trail through the bush along the Umgeni River.

There I could relax, cruising at about 50km/h in fourth gear, and find out that the progressive suspension was very supple for the first few centimetres, making the bike easier to steer at these gentle speeds, while the petal brakes were extraordinarily powerful given the basic design of their callipers.

Then it was on to the big kahuna, the YZ450F- a bike so powerful that the world governing body is reportedly considering reducing the upper limit for the MX1 class to 300cc.

I found it easier to ride at the very low speeds I was averaging along the enduro loop as the bigger engine has vastly more bottom-end torque (not sure how much more, Cyril, Yamaha doesn't quote power outputs for racing machines) but it never lets you forget there's a potentially lethal beast lurking under your right hand that can oh-so-easily get out of control if you get the tiniest bit careless with it.

A couple of times a moment's inattention resulted in lurid slides with the rear wheel way, way out of line and me too scared to close the throttle for fear of highsiding it.

If you want to ride the back roads at weekends or cruise the mountain trails, get an enduro bike; it'll be easier, safer and, ultimately, more fun.

If, however, getting round a motocross circuit faster than the next guy is your thing, Yamaha's YZ250F and YZ450F should be at the top of your shopping list.

Prices:

- YZ250F - R54 995

- YZ450F - R61 995

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