The high-flying, high-paced action of motocross is not for everyone. As a result, the slightly less intense world of cross country / hare scramble racing is a popular alternative. The YZ250FX is a cross-country-focused model with the performance potential of the YZ250F. If you are serious about winning, the YZ250FX could be the machine for you.
The YZ250FX uses the reversed-cylinder, rearward-slanted engine from the previous-gen YZ250F with modified fuel injection settings, electric start and a 6-speed transmission.
Featuring a KYB speed-sensitive fork and fully adjustable KYB rear shock, the FX uses the same suspension as its MX cousin with softer settings and slightly more rear wheel travel. Also included is a lightweight aluminum side stand, adjustable handlebar and an 18-inch rear wheel. .
Features & Benefits
Key features for 2019
- Latest-generation YZ250F-based, rear-slanting engine and bilateral beam chassis
- Forward-mounted fuel injection and wraparound exhaust
- Electric starting
- YZ-based, fully adjustable KYB suspension
- 18-inch rear wheel
- Adjustable handlebar
- GYTR Power Tuner compatible
"Reversed" liquid-cooled, 250 cc, DOHC, 4-valve (titanium), single-cylinder engine with fuel injection. The engine has been tuned for excellent rideability and controllability and delivers a broad, easy-to-use powerband with excellent power characteristics throughout the rev range. 2018 model changes improve power delivery in both low-to-mid and mid-to-top-end performance.
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
"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
Electric start with auto decompression system. Unit can be re-started in any gear.
NOTE: kick starter has been discontinued/removed (available as an accessory).
- 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
- removal of kick starter and related gears etc. reduces weight
Lightweight titanium valves and revised load 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
Automatic cam chain tensioner.
- reduces maintenance
- special cam chain "sliders" reduce internal friction losses
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
Lightweight piston pin features a diamond-like coating (DLC) to reduce friction.
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
"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
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
- bronze thrust washers located between crank webs and rod
- heat-treated for strength and durability
- balance ratio of the crank has been optimized for minimal vibration and good torque feeling
Nickel-chromium-molybdenum connecting rod.
- excellent strength and durability
Lightweight, gear-driven counter balancer shaft.
- reduces vibration for improved rider comfort and less rider fatigue
6-speed transmission utilizes a 2-bar, floating shift guide system and a 14 mm shift shaft.
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
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
Handlebar-mounted engine trouble and low fuel warning lights.
Optional, compact, hand held "GYTR Power Tuner" allows tailoring of both fuel injection duration and ignition mapping.
- 9 different setting points can be accessed for both fuel duration and ignition maps
- maps can be stored and shared with other Power Tuners if desired
- easy-access GYTR Power Tuner connector port
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
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
Easy access "cartridge-type" oil filter.
Compact, lightweight, single-core, YZ250F-based dual radiators.
- outstanding cooling efficiency
- pre-wired for accessory cooling fan—fits on right side rad only
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
High-capacity AC magneto eliminates need for a battery.
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
Lightweight, aluminum, re-packable muffler (aka silencer).
- sound output is 94 dB meeting AMA regulations
Works-style, race-spec "barrel adjuster" for on-the-fly clutch lever free play adjustments.
Heavy-duty plastic engine skid plate
Excessive lean angle sensor
- Will shut down the engine if the bike lays on its side
- helps prevent costly engine damage
Compact bilateral beam aluminum frame.
- frame design centralizes mass for exceptional handling and agility
- frame offers an optimum balance between strength, rigidity and tuned flex, plus excellent shock absorbing qualities
- frame design offers excellent rider-machine communication (a.k.a. feedback)
Lightweight, tapered aluminum swingarm.
- lightweight design reduces unsprung weight for excellent suspension performance
- excellent rear wheel traction and control
- large 25 mm rear axle
Lightweight detachable rear sub frame.
- constructed of square-section, lightweight aluminum pipe with no bends
- allows easy access when servicing rear suspension components
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.
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
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".
Large "wrap-around" plastic fork protectors provide excellent lower fork tube protection.
- "self-supporting" design reduces friction for smoother fork operation.
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
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
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
"Shorty-style" adjustable front brake lever can be adjusted to fit various hand sizes.
245 mm rear disc brake uses a "wave-style" disc and single piston Nissin caliper and Nissin master cylinder.
Rear caliper and lower portion of the disc are protected by heavy duty plastic protectors.
Lightweight, plastic resin 7.5 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
Handlebar-mounted engine trouble and low fuel warning lights
- 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
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
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