Yamaha: 2011 Yamaha YZ250F Dirt Bike Motorcycle

Bilateral Beam frame and compact chassis delivers superb rigidity and balance for unmatched handling

Key development concept behind the 2011 Yamaha YZ250F is excellent cornering and handling performance, to deliver a bike that’s so intuitive it knows what you are thinking, before you do.

yamaha, yamaha motorcycles, yamaha dirt bikes, yamaha yz250f, 2011 yamaha yz250fYou may not find “flickability” in the dictionary, but we measure it by how easily the machine does what the rider wants.

By that definition, what the rider wants is the YZ250F. The Bilateral Beam frame delivers superior cornering speed and stability, while the fuel tank is nestled close to the center of gravity for light handling.

This bike is so intuitive it dives for apexes exactly when you tell it to, and changes lines as quick as you can think of them.

Key Features:

* The Bilateral Beam frame is specific to the 250 and is more compact than the previous generation chassis. This places the rider closer to the front wheel, which delivers superb rigidity balance for unmatched lightweight handling and cornering.

This nimbleness lets the rider get on the gas sooner out of corners and cross the finish line with less fatigue – even on long motos.

* The optimized engine delivers a high level of power in the low-to-midrange, with a great torquey feel, exactly where riders want it. That is due to the straight intake boot that enhances breathing, carburetor that provides excellent throttle response and fuel atomization, and valve train components that reduce inertial mass and boost low end torque.

Exhaust is also enhanced with a D-shaped exhaust port. Ongoing refinement to the suspension and engine produces an amazingly balanced, light-handling machine with performance that’s accessible to all levels of riders.

* The styling emphasizes the bike’s lightweight and nimble handling character. The sharp, horizontal lines set the bike apart with a clean, aggressive look.

* KYB® suspension is tuned to work with the Bilateral Beam frame for unmatched handling. The clutch lever has a light pull feel, even though the clutch has stronger engagement. The clutch also has a wide engagement range that will give riders an advantage off the line. . . shift after shift, moto after moto.

* There’s no disputing the YZ250F’s unmatched four-stroke prowess – it was the 1st four-stroke 250 motocross bike on the market, the 1st to win an international race, the 1st to win an AMA® Supercross,® and the 1st to take an AMA® U.S. Supercross Championship® title, as well as the first to win an AMA® National race.

Engine:

* The valve spring retainers are lightweight aluminum instead of steel, and valve spring pressure is lighter for reduced valve-opening force. This contributes to superior low-to-midrange torque characteristics due to less power-robbing friction. There’s also a higher lift cam profile, while valve stem ends are chromium-nitride coated for exceptional reliability and reduced maintenance.

* The exhaust port is “D” shaped instead of round. This increases velocity through the port for excellent throttle response, while enhancing the power feeling of the engine.

* The radiator is lower and further back and the oil tank is compact and repositioned to achieve greater mass centralization.

* The carburetor bore has a venturi shape, plus there’s recalibrated jetting and an accelerator pump. This translates to impressive response when the rider snaps open the throttle, and contributes to superb torquey low-to-midrange power characteristics.

* The intake boot offers a straight, smooth tract for excellent engine breathing and more power. The airbox is shaped to tuck neatly into the Bilateral Beam frame.

* The exhaust pipe has been carefully tuned to optimize engine power, with a muffler that’s 50mm longer and with a narrower core – a design that lets the YZ250F comfortably meet the latest noise standards without sacrificing power.

* Engineers were able to increase the clutch spring load for stronger engagement, yet, thanks to a recalibrated clutch actuation arm cam ratio, lever pull is actually lighter than before.Yamaha Motorcycles

* Third and fourth gear ratios are slightly taller, and third, fourth, and fifth gears are stronger than ever with drive dog shapes for positive engagement.

That gives riders a strong gearbox that’s been carefully matched to engine power characteristics.

Chassis/Suspension:

* The Bilateral Beam frame is crafted from a carefully chosen combination of forged and extruded aluminum pieces – 20 in all – all welded together to provide unmatched rigidity balance.

* The KYB® speed-sensitive front fork delivers exceptional damping feel, responsiveness, and bump absorption characteristics. The piston rods have a new surface treatment, and the oil seal is a new design.

* The 4-way-adjustable KYB® rear shock has been designed to make the most of the Bilateral Beam frame design. It’s lower in the frame for excellent mass centralization.

* The tank, seat, and rear fender are flat and the relationship between handlebars, pegs, and seat result in a natural, more forward riding position that facilitates rider movement. The fuel tank has been moved toward the center of the bike for mass centralization. The ProTaper® bars are four-way adjustable, and handlebar mounts and footpegs are 5mm higher to optimize rider position on the chassis.

Additional Features:

* Riders have a choice of two color options: Team Yamaha Blue and White or White and Red.

MSRP* $7,250 (White/Red) Available from September 2010
$7,150 (Yamaha Blue/White) Available from September 2010

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 100/90-19

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
Fuel Capacity 1.7 gal
Wet Weight*** 224.8 lb

Other

Warranty 30 Day (Limited Factory Warranty)

If you enjoy reading our Articles, please consider leaving a comment or subscribing to the RSS feed to have future articles and News information on Motorcycles delivered to your feed reader. Thank you and have a great day!

Comments are closed.