See the bike in action Click here for the video of Doug Dubach in action on the new Milestone Ranch MX Park.
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Last week in Riverside, CA, we got a pair of sneak previews. One was of the 2007 Yamaha YZ250F, while the other was of a new track wedged nicely between San Bernardino and Riverside, the Milestone Ranch MX Park.

First Look: 2007 Yamaha YZ250F

Of course, the bike is what we came to focus on, and Yamaha had three targeted areas in mind for improvement on the quarter-liter thumper, including boosting engine performance, reducing weight, and improving the handling, so let's check out each area.

Engine Performance

A host of changes were on Yamaha's list for the five-valve four-stroke, to improve top end and over-rev, all the way up to 13,500 RPM. They included a new carb accelerator pump setting for the 37mm Keihin FCR flat-slide, designed to eliminate hesitation when the throttle is cracked open quickly, along with different internal settings on the carb. The carb itself is now mounted using a three-bolt intake mount, rather than the traditional hose clamp setup.

First Look: 2007 Yamaha YZ250F

Here's the layout of the new carb mounting setup.

The new exhaust silencer end-cap has a longer tailpipe that meets the AMA sound regulations and also aids the engine over-rev.

The '06 end cap is on the left, and the '07 is on the right.

And last but not least, a gearing change from 13/48 to 13/49.

For software fans and tech geeks, there has also been a revision to the ignition mapping.

Weight Savings

Nearly three pounds of fat were trimmed from the '07 version of the 250F, from areas as diverse as the seat foam (changed from Polyurethane to Polypropylene), to changing from brass to aluminum threaded inserts in the gas tank. Or you could point to a new radiator hose layout, a lighter subframe, and lighter chassis hardware, including 25 bolts with matching head sizes, which will definitely make mechanics happier.

The new radiator layout on the 2007 YZ250F is taller, wider, and thinner than its predecessor, and besides being a claimed 20% lighter than the 2006 version. They also have new vanes and plumbing to eliminate any sacrifice in cooling, along with added reinforcements to boost impact protection.

The rear shock is another area where weight was trimmed, as brass damping adjusters were replaced with aluminum units. The weight-trimming titanium rear spring carries over from the previous model.

Adding to the weight savings is a new oil tank with improved protection and a lower mounting point, a magnesium clutch cover, lighter chain guide and guard, and chain adjustment components.

Want more? How about a few components in the front end that were changed to trim additional weight, including a new front brake caliper that's more compact and uses a forged mount, along with smaller front axle brackets on the 48mm Kayaba forks.

The '06 front brake caliper is up top, while the smaller and lighter '07 is on the bottom.

Even the braking components were put on a diet, with a lighter pushrod-style front brake lever, and wave rotors front and rear.

You've now got lighter wave rotors on the front and rear of the '07 YZ250F.

Lightweight Handling Feeling

In the search for a lightweight handling feel, Yamaha changed quite a few things. The mounting angle of the engine was changed to rotate the cylinder head closer to the center of gravity, the steering head was also moved back 3mm, and the shock length was increased by 1.5 millimeters. The result of all these changes is more weight centralization and a steeper fork angle aids quicker turning.

The blue outline here shows the '06 frame layout, while the red is the '07. You can see how the engine mounts have moved to rotate the engine back, and how the head tube was moved back 3mm.

Other changes in the ergonomics include a different bend of ProTaper bars that add four millimeters to the sweep (from 50mm to 54mm), and boost the height of the bars (from 79mm to 87mm).

The ProTaper bars are taller and slightly more swept back than in the past.

The bottom triple clamp was changed from a cast piece to a forged unit that's smaller and lighter, and the handlebar mounts have changed from cast to forged as well.

The combined result of all the changes to the chassis and ergos is to put more weight on the front wheel for improved cornering, and improving mass centralization to improve the handling.

Cornering capability? Check out Doug Dubach railing this sand berm

Cost and Availability

Depending on whether you want a traditional blue/white combo, or the optional white/silver color scheme, you'll pay either $6,149, or $6,249, and the bikes will be available in November.

Our suggestion? If you get one, be the first to write a review on it in the Product section, and let everyone know what you think.

Oh, and be sure to check out the video of Doug Dubach in action on the new YZ250F, and for more on the track that he's riding, be sure to check out the web site for Milestone Ranch MX Park at www.milestonemx.com.

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