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Ride Impression: 2010 Yamaha YZ250F

Ride Impression: 2010 Yamaha YZ250F

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Ride Impression: 2010 Yamaha YZ250F
Vital MX Ride Impression: 2010 Yamaha YZ250F

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What do you do when you’ve got a perfectly prepped track (Washougal in this case), a brand new YZ250F, and a day-and-a-half free to test it?

Ride it like you stole it, that’s what.

The 2010 Yamaha YZ250F in one of the most scenic settings around, Washougal Motocross Park. Click this image (or an other one in the article) for a larger version.

Yamaha invited us up to get a first look at the new 2010 YZ250F, and we brought along privateer Scott Champion to check it out. While Scott’s been racing a Honda at the Nationals this season, he most often practices during the week on an ’09 YZ250F, and we figured he’d be able to provide good feedback on the bike.

During Yamaha’s presentation on the changes to the new bike, a lot of the items mentioned revolved around the new aluminum frame, which they dub as “bilateral beam”. It’s combination of extruded and forged components is said to add both lateral and torsional rigidity. They’ve also gone to two mounting points between the engine’s head and the frame, which further stiffens up the chassis.

Scott dug the cornering on the new blue 250F.

But while the chassis is new, they haven’t ignored the engine. Time was spent straightening the intake tract by doing things like moving the shock spring lower to free up more room, and moving the filter to the left. They also changed the carb to a new model with a smoother venturi shape to get the 250F to breathe. A new accelerator cam shape was added to provide better response when you crack the throttle quickly.

They also added a new cam, new coatings at the end of the valve stems designed to extend the time needed between valve adjustments, and changed to a lighter spring load in the valves. They were able to do that by switching from a steel valve spring retainer to an aluminum version.

On the exhaust side, they reduced the size and shape of the exhaust port. While the size is smaller, the velocity got boosted. They also changed the pipe; and the length of the muffler, along with the pitch of the holes in an effort to reduce noise output without reducing power.

As for the clutch, they boosted the spring load, but increased the leverage ratio of the clutch pull by a greater amount, so the net result is a lighter feel to the pull.

The 2010 YZ250F will pull longer in harder in third and fourth gear, partly due to changes in the transmission ratios.

Talking with the Yamaha crew, they let us in on one interesting fact. All the test bikes get a break-in period, and are run on a dyno before they’re handed off to media outlets. While there used to be a wider variance in performance from bike-to-bike in among the two-stroke models, the difference in performance between the 12 YZ250Fs currently in the country falls within a very small range.

While we’d guess that 250Fs with carbs might not have the sex appeal of the new EFI systems, Yamaha’s closing in on ten years of experience with production 250Fs, and they have no shortage of experience with fine-tuning the bikes. The 2010 is an extension of that experience.

One of the goals of the Yamaha development crew was to make the bike more flickable. Looks like they accomplished that.

As far as the other big change for the year, the new bodywork and the looks of the bike, we’ve seen some of your comments in the Vital MX Forum. It seems people have either loved it or hated their first impression of the 2010 model. While it is very different looking than your traditional Yamaha, we also got to spend some time around the bike while it was being displayed at National at Washougal, and the comment we heard most often was, “It looks a lot better in person than in the photos.” We’d wholeheartedly agree with that. It’s lean, mean, and minimalistic. The flatter seat is easier to move around on, and they did a lot of work to centralize the weight…moving the radiators rearward and lower, and narrowing the tank. That definitely makes it easier to move around on. The ride position is a little further forward than in the past, and there are provisions to allow you to move the bars forward or back over a 30mm range. For his time on the bike, Scott preferred them further back, and liked the changes it made when he made that adjustment.

Riding on a closed day at Washougal? Epic.

As far as suspension, the KYB Speed Sensitive fork gets new damping settings, along with a new seal shape, and new surface treatment on the piston rod. In the rear, the spring has been lowered on the shock body to provide extra room for the airbox intake, and doubles up by lowering the center of gravity. It also gets some damping spec updates.

So did Yamaha make steps forward with their new 250F? Among Scott’s primary comments? That it’s definitely faster, and pulls longer in third and fourth. It has more low end (something that Yamaha had been trying to achieve with all their changes), and it also handles better through the corners. But you can check out the video (see the link above) to get his first-hand comments.

2010 Yamaha YZ250F Specs

Engine

Type
250cc liquid-cooled DOHC 4-stroke; 5 titanium valves
Bore x Stroke
77.0mm x 53.6mm
Compression Ratio
13.5:1
Fuel Delivery
Keihin® FCR MX37
Ignition
CDI
Transmission
Constant-mesh 5-speed; multiplate wet clutch
Final Drive
Chain Drive

Chassis

Suspension/Front
Speed-Sensitive System inverted fork; fully adjustable, 11.8-in travel
Suspension/Rear
Fully adjustable single shock; 12.0-in travel
Brakes/Front
Hydraulic single disc brake, 250mm
Brakes/Rear
Hydraulic single disc brake, 245mm
Tires/Front
80/100-21
Tires/Rear
110/90-19

Dimensions

Length
85 in
Width
32.5 in
Height
51.3 in
Seat Height
38.9 in
Wheelbase
57.7 in
Ground Clearance
14.8 in
Wet Weight
224.8 lb
Fuel Capacity
1.7 gal

Other

Warranty
30 Day (Limited Factory Warranty)
MSRP
To be announced Fall 2009.

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