Yamaha's newest motocross bike is ready for Dirt Rider Magazine's first full test. Are you? You might think you are. But are you really ready? We sure hope so...
Chris Barrett welcomes the 2009 YZ250F to its new home: The Dirt Rider Magazine Testing Fleet.
We rode the 2009 YZ250F. And then we rode some more. Then, for good measure we went out and rode it again. All told we dropped well over 7 hours onto the hour meter of our new bike and we keep getting happier with the new YZ. Here's every little thing we know about it.
What's New
Chassis:
--The biggest change everyone is talking about is clearly the subtle-to-the-eye swingarm and linkage refinements. The 2009 YZF linkages are hydro formed, dented, tweaked and tuned to provide more flex up and down, less flex left to right and more flex independently up and down like a swimmer kicks his legs. Get it? Basically, the whole rear wheel chassis program is designed to flex optimally to provide traction and comfort and not flex optimally to keep the bike stable in turns.
The 2009 Yamaha YZ250F waits patiently for Dirt Rider Magazine's first test.
--The rear shock spring is no longer titanium. It's now a more affordable steel spring.
--The rear hub is more compact and built to hold the newer, beefier 25mm diameter rear axle ('08 axle was 22mm) with it's three new bearings. There are two bearings on the drive/sprocket side and one on the brake rotor side. This redesign was intended to reduce unsprung weight and deliver a more freely spinning rear wheel.
--The Front tire is now a Yamaha Exclusive Bridgestone M403A. It's reportedly identical to a M403 yet with a flatter profile with sharper edges. It's basically not as domed. The idea here is to give lighter steering feel without sacrificing traction.
While the linkage ratio stays the same on the 09 YZ250F, the flex character of the swingarm and linkage provide a much improved ride in the corners. The bike now stays where you put it. Oh, the gold chain is fancy, too.
--The new top triple clamp now makes different bar positions an option. The standard position is 5mm back from 2008 and is adjustable in 10mm increments. From standard you can drop it back 10mm, forward 10mm or way forward 20mm for an overall range of 30mm.
--The bar mounts are now identical to the YZ450F units and are 4mm taller than the 2008 250F mounts.
Engine:
--The YZ250F exhaust system receives a complete makeover for 2009. The header tube gets the most intense treatment and is now 60mm longer than the 2008 model's pipe. It's longer in the section right out of the motor. Also, instead of the mid-section being stepped (from a 45mm section to a 50.8mm section) the 2009 model has a solid 50.8mm diameter mid pipe all the way through to the muffler. Improving power delivery is always a good reason to tweak header pipes and this is exactly why Yamaha tweaked theirs.
Exhaust system changes start at the header with a longer section before it bends.
--The Muffler receives changes in the opposite direction and loses 50mm to its overall length. Shortening mufflers does a couple different things. It tunes power and saves weight, but more importantly it moves weight from up high and out-of-center to closer to the spinning mass of the vehicle.
--Internally, the '09 YZ250F clutch assembly is totally new. By ditching the judder-spring laden inner basket assembly in favor of a rubber damper setup, Yamaha did quite a bit. They made maintenance easier by making all the metal plates identical throughout and reduced oil contamination by eliminating any metal plate-on-judder spring wear. We're enjoying some power delivery benefits from this change as well. Read on...
--Carburetion changes include a richer needle than '08 and a leaner fuel screw setting to boost the low end power and pump up throttle response.
Controls and styling:
The new Yamaha 250F muffler is shorter. More power? Yeah, a little. But there is a big handling benefit to shortening a muffler. Any weight out of center you can eliminate is a good thing.
--The control end of the clutch system is updated. The all new perch features reach adjustment to the lever via set-screw-type movement and is a stronger overall perch. Quick-adjustment of clutch tension is now as simple as other brands with fewer moving parts making it much easier to disassemble, clean and reassemble. The clutch lever itself is a bit shorter for comfort and the lever-perch junction is of closer tolerance to keep annoying clutch-lever rattle down.
--Both the Hot Start Cable and Throttle Cables have tool-less tension adjustment to take out or add cable slack.
--The chain is blinged out with a gold anti-rust coating. Cool looks are still cool.
--The seat has a grippier gripper seat cover and is easier to keep clean since it resists stains.
--Black clutch and ignition covers return for a second year and have infected the valve cover with their darkness.