The sky's the limit for Yamaha
By TMX Archives on 10th Sep 09
YAMAHA was at the forefront of the four-stroke revival - which rapidly turned into four-stroke domination - of motocross, firstly with its eye-opening YZ400F and shortly after with its quarter-litre sibling. Then it sort of sat on its laurels a bit while everyone else caught-up. But 2010 is looking like the year when Yamaha moves the goalposts again. There's a hot new 450Fcoming up shortly but meanwhile, the 250F has been given a snazzy new chassis, a sharp new look - and a whole new lease of life. Read on...
THE 2010 bike tests are coming thick and fast now and recently I got the chance to get a shot on the radically changed 2010 Yamaha YZ250F at Doncaster Motopark. Now, I thought that Yamaha had been in need of a face lift for a while now as they have looked a bit boring for the last few years with the stodgy old shape of the rad scoops and the seat, which you kind of sit 'in' rather than on.
Well, for 2010 they have deffo gone for it. Not just a few minor changes but a whole bunch of mods. In fact I'll re-phrase that, basically Yamaha has more or less completely re designed their 250F. It now sports much sleeker-looking bodywork with really aerodynamic features - the rad scoops and tank look absolutely fantastic, similar to the shape of the new Husqavarna, very sharp looking! And the seat now just blends into the tank perfectly and when you're sat on it, you actually feel like you are sat ON it, rather than in it like last year's bike.
Also, the seat cover on the new-shape seat offers the perfect combination of grip yet couples with ease of sliding that allows the rider easy control of the bike but still with reassuring grip when needed i.e in muddy conditions. All the rest of the plastics on the new bike have been re-shaped as well (which will not really please the after-market plastic/ graphic companies as none of last year's stuff will fit!) and the bike comes with new front and rear fenders, number board, fork protectors and side panels. All combine brilliantly to make the new bike, in my humble opinion, the best looking Yamaha ever!
Yamaha even offer the new bike in two colours: traditional blue or a cool-looking white so when you are ordering yours make sure you get the colour you want. Both bikes come with black anodised rims that finish the bike right off.
And to top all that off, for the first time ever the 250F has its very own purpose-built chassis/ frame. Previously the 250F has been slotted into what has been effectively a modified 450 chassis. But for 2010 it's all brand-new with what Yamaha calls a bilateral beam aluminium frame with a revised castor and trail and sub-frame. This new frame design is to give the new model a whole new feel and to make the bike turn a lot quicker. Working in conjunction with the new frame is a new set of triple clamps that come with four-step adjustable handlebars to enable you to get really far forward in the corners and make it tuck in to the berms and make it turn even tighter.
Suspension wise the front forks have been modified to work in sync with the new chassis layout. Improvements have been made to the inner rod and the damping valve to give a plusher feel when turning in to fast sweeping corners. At the rear, the position of the spring of the suspension unit has been lowered 29mm in order to deal with sharp faced bumps a lot easier and just help the 2010 YZ250F handle and corner far better than its predecessor.
Moving on to the motor department, the engine has been left pretty much the same as last year and if we are being honest, and taking into account Cairoli's performances in the GPs over previous years it's pretty damn good anyway!
All the same there have been some minor modifications including revised carburetor settings (as its not fuel injected) and this results in a more linear power delivery through the rev range and better control at low to mid speed. Also the engine's intake and exhaust valves come with lightweight aluminium retainers and new valve springs which open more easily to accommodate these changes. the carburetor settings have been optimised and the air cleaner itself has had the down tube from the air box modified to fit the new frame. The exhaust port has also been modified from a round cross-section to a 'D' shaped cross section to give the new bike a much more responsive feel. In the gearbox, third and fourth ratios have been changed to acheive optimum performance.
OK, enough of the boring specs, the bike looks mega, so lets get on it!
Once I got on the bike it only took me two laps of the track to realise what a fun bike it is to ride. All the hard work that Yamaha have done in designing the new chassis has really paid off because, I know this is a cliche but the 250F really did corner as if it was on rails!
I felt like I was able to pull myself really far forward, right up the tank, which made the me feel totally in control. In previous years I always felt like Yamahas didn't corner too great and felt that sometimes the front end kind of just went where it wanted rather than where the rider wanted it to go. The brakes are unchanged for 2010 but as always with any new bike they had a nice sharp feel to them all day and they never suffered any fade.
The position of the handlebars and the overall riding position on the new Yam made it possibly the most comfortable motocross bike I have ever cocked my leg over. Exiting corners I found I could manoeuver myself all over the bike and basically put it exactly wherever I wanted. In short, I was really, really impressed with the handling.
The front forks and rear shock were set up spot-on and worked well in conjunction with the chassis. Power-wise, although the engine hasn't undergone major surgery the small modifications it has received have definitely given the new bike a really nice sharp feel to it.
As mentioned earlier, third and fourth gear - usually the most used on a 250F - have been modified and can really notice the difference when exiting the fast corners i found that i could hang on to both gears a lot longer than on last year's bike.
The new layout of the chassis definitely made the bike really easy to chuck around over jumps and whoops and other obstacles. The overall wet weight of this bike is a claimed 102kg which is slightly heaver than some of its competitors' claimed weight - but if anything the Yam felt a lot lighter on track. I really enjoyed hurling this bike into the deep, sandy berms at the test track and just seeing how far I could push the bike, to see if it tucked-in anywhere or maybe run wide in any of the berms. I'm pleased to report that it never ever disappointed me and was an absolute pleasure to ride everywhere.
In fact, at the end of the day, one of the Yamaha technicians had to come down to the track and almost physically drag me off in order to give someone else a chance on this bike. One thing I didn't like was the standard grips as I got lots of blisters (everybody say "Ahhhh" - Ed!) but then again most people change the standard grips as soon as they they get a bike.
The 250F fired up perfectly all day long - hot or cold as you would expect - and remember it isn't fuel injected.
All in all I finished the day with a big, big smile on my face and I just have to give a big thumbs up for Yamaha - the 2010 YZ250F certainly is a cracking overall package...
TECHNICAL HIGHLIGHTS
2010 Yamaha YZ250F
CHASSIS AND STYLING
New design bilateral beam aluminium frame
Revised caster and trail
Front suspension with further maturation
Rear suspension spring position optimised
New-design flat seat
New design fuel tank
New lightweight parts
New body styling with smaller-surface exterior parts
Second colour, Competition White, offered (not available in all territories)
ENGINE
Refined engine with refined character
Aluminum retainer and low weighted valve spring
New carburettor settings and funnel shape
Modified exhaust port shape
Rigid mount silencer
Transmission ratios changed for third and fourth gears
Reduced clutch operational load
SPECIFICATIONS
2010 model Yamaha YZ250F
ENGINE
Type: Liquid-cooled, 4-stroke, DOHC, 5-valve forward-inclined single cylinder
Displacement: 250 cc
Bore and stroke: 77.0 x 53.6 mm
Compression ratio: 13.5 : 1
Max Power: N/A
Max Torque : N/A
Lubrication: Dry sump
Carburettor: Keihin FCR-MX37/1
Clutch type: Wet, multiple-disc
Ignition: CDI
Starter system: Kick
Transmission: Constant mesh, 5-speed
Final transmission: Chain
CHASSIS
Frame: Aluminium bilateral beam
SUSPENSION
Front: Telescopic forks
Travel: 300 mm
Rear: Swingarm (link suspension)
Travel: 310 mm
BRAKES
Front : Single 250 mm disc
Rear: Single 245 mm disc
TYRES
Front : 80/100-21-51M
Rear: 100/90-19 57M
DIMENSIONS
Overall length: 2,168 mm
Overall width: 825 mm
Overall height: 1,304 mm
Seat height: 991 mm
Wheelbase: 1,473 mm
Ground clearance: 377 mm
Total weight
(inc oil & fuel): 102 kg
Fuel capacity: 6.4 litres
Oil capacity: 1.2 litre
Specification: