ENGINE -
Engine Performance
- Liquid-cooled 250cc four-stroke churns out stronger mid- to high-range power
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Selectable Fuel Maps
- Increasing the YZ250FX's ability to tackle a wide range of riding environments, the ECU has been optimized with two improved fuel injection maps—both of which can be loaded and tuned in the Yamaha Power Tuner app—accessible through a handlebar-mounted map switch for on-the-fly adjustments to changing riding conditions. Pre-loaded maps include one for fast, aggressive high-traction conditions and one with a smoother engine character for extreme, low-traction conditions.
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Rearward-slanted, reversed cylinder design.
- rearward slant moves a significant amount of rotating weight toward the centre of the chassis
- rearward-slanted cylinder centralizes mass for excellent handling and a light, agile feel
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"Reversed" engine design (FI system is front-mounted, exhaust exits from rear of cylinder).
- forward-mounted FI provides straight intake path into the cylinder and provides optimum fuel/ air filling and flow for excellent power
- front-mounted intake design keeps fuel cooler since engine heat has less effect on incoming fuel (cooler fuel is more dense and increases power)
- design also helps centralize mass for light, agile handling
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Electric start with auto decompression system (no kick starter). Unit can be re-started in any gear.
- there is no main ignition switch on this model
- electric start button (RHS handlebar) activates the entire electrical system
- kill switch (LHS handlebar), if held for a few seconds, shuts down entire electrical system
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Lightweight titanium valves and optimized valve springs.
- titanium valves reduce reciprocating weight and allow for a higher rpm limit before valve float
- titanium valves means a fast-revving engine with smooth power delivery
- 31 mm titanium intake valves and 25 mm titanium exhaust valves
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Automatic cam chain tensioner.
- reduces maintenance
- special cam chain "sliders" reduce internal friction losses
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Lightweight, short-skirt, forged aluminum piston.
- light flat-top piston features lateral ribs on both sides of the piston pin area
- single compression ring and specially designed oil control ring increases surface contact area for optimal sealing
- 2-ring design decreases sliding resistance, reduces weight and provides faster throttle response
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Lightweight piston pin features a diamond-like coating (DLC) to reduce friction.
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Piston oil cooler jet nozzle directs oil to the desired portion of the cylinder and underside of piston.
- reduces piston, cylinder and rod temperatures for excellent durability
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"Liner-less" lightweight aluminum cylinder with ceramic composite coating.
- ceramic coating sprayed directly on the aluminum block, eliminating the need for a liner and reducing weight
- excellent heat dissipation for consistent power delivery
- coating enhances the thin film of oil between cylinder and piston, reducing friction and increasing power
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Cylinder and crankcase "cutaways" allow air "trapped" under the piston to enter special chambers or cutaways.
- reduces horsepower-robbing "pumping losses"
- crankcase cutaways match cylinder cutaways for maximum efficiency
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Ball-bearing-style crankshaft.
- bronze thrust washers located between crank webs and rod
- heat-treated for strength and durability
- balance ratio of the crank is optimized for minimal vibration and good torque feeling
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Nickel-chromium-molybdenum connecting rod.
- excellent strength and durability
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Lightweight, gear-driven counter balancer shaft.
- reduces vibration for improved rider comfort and less rider fatigue
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6-speed transmission utilizes a 2-bar, floating shift guide system and a 14 mm shift shaft.
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Heavy-duty, multi-plate clutch features a quick access magnesium outer cover.
- low-friction bushing on actuation arm reduces lever pull effort
- clutch is designed for the rigours of cross-country
- outer cover provides fast and easy clutch access
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44mm Keihin throttle body fuel injection system.
- 10-hole injector
- maximizes fuel atomization for optimal combustion and excellent power delivery
- FI benefits include automatic adjustments to insure the optimum fuel - air ratio regardless of outside air temperature and altitude
- other benefits include excellent starting and excellent throttle response
- cold start knob also doubles as an idle adjuster
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Handlebar-mounted engine trouble and low fuel warning lights.
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Exclusive Power Tuner app.
- Groundbreaking technology brings the power of the GYTR Power Tuner to your iOS or Android device
- onboard wifi allows adjustment of air/fuel mixture and ignition timing maps based on track conditions
- record race log information and monitor a range of data such as maintenance and system diagnosis, engine run time and more
- CCU is adopted to accommodate new Power Tuner
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Forward-mounted air box features a washable, dual-stage, foam air filter.
- airbox cover features flush mounted quick release fasteners
- no tools required to access air filter
- washable foam filter reduces tune up costs
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Wet sump lubrication system.
- reduces weight (no remote oil tank or oil lines)
- eases maintenance (easier and faster oil changes)
- oil volume is optimized to reduce oil related drag and weight
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Easy access "cartridge-type" oil filter.
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Compact, lightweight, single-core, YZ250F-based dual radiators.
- outstanding cooling efficiency
- pre-wired for accessory cooling fan - fits on right side rad only
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Maintenance-free transistor controlled ignition (TCI).
- produces a strong spark for fast starts
- provides precise ignition timing / mapping for optimum engine performance at all rpms
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High-capacity AC magneto eliminates need for a battery.
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Wrap-around exhaust system to match head, cam and intake.
- exhaust exits from the rear of the engine and circles cylinder body
- wrap-around design ensures the optimum tuned header length
- maximizes exhaust "pulse effect" for excellent power delivery
- centralizes mass by moving weight closer to the centre of the chassis
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Lightweight, aluminum, re-packable muffler (aka silencer).
- sound output is 94 dB meeting AMA regulations
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Works-style, race-spec "barrel adjuster" for on-the-fly clutch lever free play adjustments.
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Heavy-duty plastic engine skid plate
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Excessive lean angle sensor
- Will shut down the engine if the bike lays on its side
- helps prevent costly engine damage
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CHASSIS/SUSPENSION -
Bilateral Aluminum Frame
- The highly developed aluminum bilateral beam frame taken from the class-leading YZ250F has been tuned for cross country performance and modified to match the more powerful engine.
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Modified Balancer Position
- Position of the balancer weight has been adjusted to reduce vibration in the low- to mid-rpm range for less rider fatigue and increased long-distance comfort.
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Lightweight, tapered aluminum swingarm.
- lightweight design reduces unsprung weight for excellent suspension performance
- excellent rear wheel traction and control
- large 25 mm rear axle
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Lightweight detachable rear sub frame.
- constructed of square-section, lightweight aluminum pipe with no bends
- allows easy access when servicing rear suspension components
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YZ250F-based, 48 mm, adjustable, inverted, Kayaba "SSS" cartridge fork offers 310 mm (12.2") of wheel travel.
- fork seal design features a scraper for better cleaning performance in muddy conditions
- valving and settings are optimized for cross-country racing
- front fork adjustments include: 20-way compression damping and 20-way rebound damping
- optional fork springs are available through Genuine Yamaha parts.
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Fork features a twin-chamber, "Speed Sensitive System" design
- damper unit is in a separate structure (completely separated air and oil chambers)
- helps prevent aerated fork oil from entering the inner damper assembly and degrading its damping abilities
- since the inner damper is pressurized; it also eliminates bubbles forming in the oil
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Fork also features a Transfer Control Valve (TCV).
- TCV enhances damping from mid to full stroke and improves bottoming characteristics
- TCV offers more precise control throughout the full suspension stroke
- TCV is located on the upside of the spring and its function is controlled by piston speed, not piston position, hence the term "Speed Sensitive System fork".
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Large wrap-around plastic fork protectors provide excellent lower fork tube protection.
- self-supporting design reduces friction for smoother fork operation.
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YZ250F-based, Monocross link rear suspension features a fully adjustable Kayaba piggyback shock with 318 mm (12.5") of wheel travel.
- valving and settings are optimized for cross-country racing
- shock features separate adjusters for high- and low-speed compression damping
- shock adjustments include: threaded spring preload, 20-way low-speed compression damping, 2 turns of high speed compression damping and 30-way rebound damping
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Adjustable handlebar holders offer a total of 4 different handlebar positions with an adjustment range of 30mm.
- suits wide variety of rider sizes
- handlebar holders are rubber mounted for reduced vibration and improved rider comfort
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Large 270mm floating front "wave-style" disc and compact Nissin twin-piston caliper.
- wave disc design reduces weight and improves cooling
- high-friction brake pads
- excellent braking performance
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"Shorty-style" adjustable front brake lever can be adjusted to fit various hand sizes.
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245 mm rear disc brake uses a "wave-style" disc and single piston Nissin caliper and Nissin master cylinder.
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Rear caliper and lower portion of the disc are protected by heavy duty plastic protectors.
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Lightweight, plastic resin 8.2 litre fuel tank is located under the seat.
- reduces centre of gravity and centralizes mass for exceptional handling performance
- tank can be flipped on its back without disconnecting fuel line (easy servicing under the tank)
- compact in-tank electric fuel pump
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Handlebar-mounted engine trouble and low fuel warning lights
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Compact bodywork.
- minimizes weight and enhances the lightweight feel and look of the YZ250FX
- flat design, "minimal" bodywork allows for fast, easy rider movements and a natural riding position
- minimal design aids in keeping the body looking good (less plastic to scratch or damage)
- graphics are impregnated directly into the plastic rad shrouds and will not peel off or get damaged by pressure washing
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Flat seat design.
- provides easy rider movements
- features a "cap cover" to access the fuel cap
- non-slip seat cover material resists clogging with dirt or mud
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Rugged, 21" (1.60 x 21) front and 18" (1.85 x 18) D.I.D. rear rims.
- excellent durability
- reduce unsprung weight for optimal suspension performance and handling
- 18" rear wheel improves puncture resistance (Vs. 19" designs)
- Dunlop AT81 tires
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Shop New 
This Cross Country racer has all the features to win including the smartphone Power Tuner app that adjusts the bike's settings to fit your style and the track. Based on the championship-winning YZ250F and boasting a wide range of cross-country features, the YZ250FX is a true "out-of-the-box" hare scramble/cross-country competition machine.