Motorcycle specifications YamahaYZ 250 F 2017 Performance overkill

enriching the winning YZ gene pool

with its new inverted cylinder head engine, this revolutionary Yamaha YZ 250 F proved it had what it took to outperform the toughest competition. This cross-country bike that rewrites the rules of the game enshrined Jeremy Martin as winner of the AMA 250 motocross championship over two consecutive years in 2014 and 2015, while Cooper Webb, the rider of the YZ 250 F, also won AMA 250SX West twice in 2015 and 2016.

yZ 250 F 2017: stronger, faster and more flexible

for the 2017 model year, the YZ 250 F benefits from a whole range ofof important technical changes, including its all-new inverted cylinder head, aimed at boosting performance while improving the two-wheeler's ride.

improvements on the 2017 YZ 250 F

- Increased pulling power at mid and full throttle
- Improved acceleration
- Smoother shifting and clutch feel
- Refined handling and suspension for greater stability and optimized control
- Improved braking power

yZ 250 F ENGINE

perfected intake and exhaust efficiency combined with a smoother a smoother gearbox and a remapped ECU, the engine of this 2017 version offers a significant increase in competitiveness.

all-new cylinder head with enhanced performance

thanks to its forward-facing intake and rearward-facing exhaust, the YZ 250 F's state-of-the-art inverted cylinder head offers a number of advantages over a conventional design. a conventional design, namely increased intake and exhaust efficiency, better mass centralization thanks to its top-access air filter and fuel tank located under the seat. For the 2017 model year, Yamaha's engineers have increased this cutting-edge technology tenfold and developed a new inverted cylinder head that offers the YZ 250 F rider increased pulling power at mid and full throttle.

restructured intake port and higher-lift camshaft

to increase the flow of fresh air to the four-valve cylinder head, the position of the intake port has been straightened and the diameter of the intake valve enlarged. The new arrangement of intake and exhaust camshafts increases valve lift for a more powerful feel from mid-range onwards. And to boost low-speed performance, the intake camshaft timing angle has been reduced.

stronger valve springs and new connecting rod

to go hand in hand with this increase in camshaft lift, stronger intake and exhaust valve springs have been fitted to the 2017 model. Likewise, the connecting rods have been redesigned to accompany the engine's increased performance, and an all-new nickel-chromium-molybdenum connecting rod is now responsible for transmitting all this force.

shorter intake cone and new throttle seal

this clear increase in power in the mid- and high-speed ranges is also due to a shorter intake cone to reduce pumping losses, while the new internal design of the intake cone promotes better fuel evaporation. In addition, the use of a larger throttle seal between the injector and the intake port increases cross-sectional area by 5%.

redesigned exhaust port and new, larger-bore front pipe

to achieve a perfect balance between intake and exhaust, both exhaust ports have been redesigned.to achieve the perfect balance between intake and exhaust, both exhaust ports have been redesigned, and the snake-type front pipe has been fitted with a larger-diameter front section. In addition to a larger bore, this front section also benefits from a more open radius of curvature, which has increased the internal cross-section to create a much more powerful exhaust pulsation effect.

new remapped ECU

to match the enhanced engine performance achieved by this new cylinder head, and the renewed efficiency of the intake and exhaust systems, we have remapped the ECU.and exhaust systems, the 2017 YZ 250 F features a new, redesigned ECU with revised ignition timing and new fuel injector configuration. The new ECU kicks in at high revs and includes a limiter that offers improved over-rev feel.

yamaha Power Tuner

riders of all levels can use the optional Yamaha Power Tuner box to fine-tune the YZ 250 F's power characteristics. This compact device plugs directly into the two-wheeler without the need to carry a PC, and allows the rider or mechanic to fine-tune the engine in the blink of an eye to match its performance to circuit conditions.

extremely robust crankcases

to cope with the increased power of its new engine, the YZ 250 F is equipped with modified, much more resistant crankcases. Although their external shape and construction are the same as those of the versions fitted to the 2016 model, the cast aluminum crankcases of the 2017 model have undergone a heat treatment that has increased their robustness by around 5% and enhanced their reliability and durability.

smoother transmission

to accompany the optimized driving force of its ultra-powerful engine, the 2017 YZ 250 F is equipped with a new transmission with wider teeth on the 2 and 3 gears.
The shape of the 1 , 3 and 5-speed clutches has also been modified - as has the design of the shift cam, clutch lever and axle style - for smoother, quicker shifting. Finally, the even greater rigidity of the gearshift lever gives a more positive feel when shifting gears.

key engine changes on the YZ 250 F

- New high-performance cylinder head
- Revised shape of exhaust and intake ports
- Larger intake valves
- Higher-lift intake and exhaust camshafts
- New valve spring design
- Completely redesigned connecting rod
- Revised gas pedal seal
- Modified air filter gasket design
- New large front exhaust bore
- New remapped ECU with rev-limiting settings
- Heavy-duty crankcases
- Redesigned clutch lever
- Redesigned gearshift cam
- Redesigned gear selector

yZ 250 F FRAME

the YZ 250 F's top-mounted air filter and under-seat fuel tank, made possible by the use of an inverted-cylinder-head engine, contribute to the refocusing of the masses. the top-mounted air filter and under-seat fuel tank on the YZ 250 F, made possible by the use of an inverted-head engine, contribute to the re-centering of mass, making the two-wheeler more agile and responsive to ride. These frame modifications introduced in 2017 result in a new balance of frame rigidity, a lower center of gravity and improved suspension.

refined aluminum frame

thanks to feedback from its teams, Yamaha has been able to refine its frame architecture to ensure that YZ 250 F riders are fully able to exploit the improved engine performance of the new 2017 model. Compared to the 2016 design, the 2017 frame is around 12 mm wider in the area behind the swingarm pivot point, and this increased balance of stiffness ensures better handling.

steel engine mounts

the YZ 250 F offers specially designed front and top brackets to complement the high torque of its 250cc engine. With two 8mm-thick steel front brackets and 6mm top brackets, the new YZ 250 F frame gives a better distribution of overall rigidity, for exceptional handling and rideability.

repositioned footrests

to leave more riding space for the rider and accommodate as many people as possible, the position of the footrests on the 2017 YZ 250 F has been lowered by 5 mm. This new feature contributes to lowering the two-wheeler's center of gravity to increase rider control on corners.

optimized suspension settings

riding ease and comfort have been perfected on the 2017 YZ 250 F thanks to several modifications to the front and rear suspensions. The unique KYB® air/oil-separated (AOS) fork features a redesigned tee with increased rigidity and a slightly reduced oil capacity.these, together with a fine-tuned factory suspension setting, give the rider a better perception of performance and frame stability in ruts, bumps and corners.

new rear disc material

for an even more powerful braking feel, the 245 mm rear disc is now made from the same heat-resistant steel as the 270 mm front disc, offering absolute braking confidence on the fastest circuits.

new graphics

the 2017 model retains its black rims but dresses up with new graphics on its covers and mudguards for a professional factory look.

main frame changes for the YZ 250 F

- Refined double-beam aluminum frame
- Redesigned, stiffer fork crowns
- New suspension settings
- Repositioned footrests
- New rear disc material
- New graphics on covers and mudguards

News and media credits: Yamaha Motor Europe and Yamaha Motorcycles USA