Motorcycle specifications YamahaYZ 250 F 2018 Performance overkill

For Yamaha cross-country riders, 2018 was all about the 450. The 2 and a half won't mind, as it was last year's star performer. And its aura is intact, with its inverted-head engine installed last year. This revolutionary Yamaha YZ 250 F has shown it has what it takes 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 the AMA 250SX West twice in 2015 and 2016.

yZ 250 F: stronger, faster and smoother

for the 2017-2018 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 rideability.

improvements on the YZ 250 F

- Increased pulling power at mid and full throttle
- Improved acceleration
- Smoother gear changes and smoother 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, this version's engine offers a significant increase in competitiveness.

all-new cylinder head for 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, including increased intake and exhaust efficiency, better mass centralization thanks to a top-access air filter, and a fuel tank located under the seat. Yamaha engineers have taken this cutting-edge technology tenfold and developed an 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 layout of the 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 this model. Likewise, the connecting rods have been redesigned to match the engine's increased performance, with an all-new nickel-chromium-molybdenum connecting rod 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 its internal design 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 made it possible to increase the internal cross-section to create a much more powerful exhaust pulsation effect.

remapped ECU

to match the enhanced engine performance achieved by this cylinder head, and the renewed efficiency of the intake and exhaust systems, the ECU has been remapped.of the intake and exhaust systems, the YZ 250 F features a redesigned ECU with revised ignition timing and fuel injector configuration. The ECU is triggered at high revs and includes a limiter for 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

the YZ 250 F is equipped with modified crankcases that are much more resistant to the increased power of its engine. Although their external shape and construction are the same as those of the versions fitted on the 2016 model, the cast aluminum crankcases on this 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

- High-efficiency cylinder head
- Revised shape of exhaust and intake ports
- Larger intake valves
- Higher-lift intake and exhaust camshafts
- Valve spring design
- Completely redesigned connecting rod
- Revised gas pedal seal
- Modified air filter gasket design
- Large front exhaust bore
- Remapped ECU with rev-limit 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 this model's improved engine performance. Compared to the 2016 design, the 2017-18 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 250 cm³ engine. With two 8 mm-thick steel front mounts and 6 mm upper mounts, the YZ 250 F frame provides a better distribution of overall rigidity, for exceptional handling and rideability.

repositioned footrests

to give the rider more riding space and to accommodate as many riders as possible, the position of the YZ 250 F's footrests has been lowered by 5 mm. This feature lowers the two-wheeler's center of gravity to enhance rider control on corners.

optimized suspension settings

the YZ 250 F's rideability and comfort have been enhanced by a number of 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.this, together with the factory suspension fine-tuning, gives the rider a better perception of performance and frame stability in ruts, bumps and corners.

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.

main frame changes on the YZ 250 F

- Refined aluminum frame with bilateral beams
- Redesigned, stiffer fork crowns
- New suspension settings
- Repositioned footrests
- Rear disc material

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