KEY FEATURES

The YZ250X is based on the YZ250 2-stroke with the following additional features that enhance its competitiveness for cross country racing / riding.

• "Re-tuned" engine Vs. YZ250 (head, ignition, porting & YPVS)
• Wider ratio transmission gears Vs. YZ250 (3rd gear & higher)
• Heavy duty clutch
• Expansion chamber shape
• Unique front & rear suspension settings
• 18" rear wheel
• Aluminum side stand
• On-off-reserve fuel petcock

ENGINE

• Lightweight, compact, liquid-cooled, 249cc, piston-reed-valve-inducted, 2-stroke.
• • super crisp, instant "right now" engine power (when in the "power band")
  • easy & economical to maintain, service & rebuild
• Key engine differences Vs YZ250.
  • revised cylinder head volume Vs. YZ250 (slight increase in volume Vs. YZ250)
  • 7.9:1 compression ratio (slightly less than YZ250)
  • revised YPVS power valve (actuation rpm & shape)
  • revised exhaust port (main) size & timing
  • wider 3rd, 4th & 5th gears ratios
  • expansion chamber front diameter (reduced)
• Lightweight, flat top forged aluminum piston.
  • excellent durability
  • light weight means fast engine response
• "Liner-less", ceramic composite cylinder bore with ceramic coating sprayed directly on the aluminum block.
  • excellent heat dissipation
  • reduced weight (no heavy iron liner)
  • reduced friction
  • extended cylinder life
• Lightweight, ball bearing style crank.
  • lightweight design for fast throttle response
  • friction reducing crank seals
• YPVS power valve system features a total of three slides (one main and two auxiliary slides).
  • YPVS system varies the exhaust port height & timing based on engine rpm
  • provides the benefits of both solid, low rpm power delivery & strong top-end punch
• Keihin PWK38S carburetor with power jet & throttle position sensor (TPS).
  • precise fuel - air mixing
  • extra-crisp throttle response throughout the powerband
• Special-design, 4-petal, carbon fiber reeds.
  • excellent throttle response & engine performance across the entire RPM range
• Smooth-shifting, wide ratio 5-speed transmission.
  • ratios are matched to engine output for maximum performance
  • optimal hook-up for outstanding acceleration & corner-exiting power
  • transmission features "involute splines" for smooth, positive shifting even under power
  • wider 3rd, 4th & 5th gears ratios (Vs. YZ250) ... see spec sheet
• Heavy-duty, multi-plate clutch.
  • Clutch spring load is reduced for easier clutch lever pull Vs. YZ250 (less fatigue)
  • quick-access, outer clutch cover allows for fast, easy clutch maintenance
• CD (capacitor discharge) ignition system.
  • delivers a precise spark for fast, sure starts
  • ensures optimal timing at all rpms for fast, strong response
• High capacity, washable, dual-stage, foam air filter.
  • excellent filtering qualities
  • reduces maintenance costs ... foam filter is re-useable
• Large-capacity, dual radiators feature 10-row cores.
  • maximum cooling efficiency
• Lightweight exhaust system.
  • computer designed expansion chamber provides maximum engine performance
  • lightweight, aluminum silencer is re-buildable for optimum performance & reduced noise levels
  • sound output is 94 dB
• Works-style clutch lever & race-spec "barrel adjuster."
  • light, easy lever pull
  • lever position (reach) can be set to rider's preference
  • for on-the-fly clutch adjustments

CHASSIS/SUSPENSION

• Lightweight, aluminum, semi-double-cradle frame.
• • combines with compact engine to provide an awesome power to weight ratio
  • obvious benefit of an aluminum frame is a significant weight reduction
  • Yamaha maintains the semi-double cradle design because it offers an excellent "rigidity balance" between lateral & torsional rigidity while offering controlled flex in the longitudinal plane
  • result is a light aluminum frame, which provides excellent handling, good ride quality, excellent stability & responsive cornering performance
• Removable rear subframe.
  • constructed of square-section, lightweight aluminum
  • detachable design allows easy access when servicing rear suspension components
  • reduces costs in the event of a loop out
• Lightweight, tapered design aluminum swingarm.
  • produced by "hydro forming", a forming method that uses high pressure water to form shapes
  • excellent rear wheel traction & control
  • lightweight design
• Cast aluminum upper and forged lower triple clamps.
  • strong yet lightweight
  • fast, agile handling
• Adjustable handlebar mounts.
  • allow handlebar to be moved 10mm rearward if desired
• "Speed Sensitive System" 48mm, adjustable, inverted, "twin chamber" KYB fork. Front wheel travel is 300 mm (11.8").
  • twin chamber design means the damper unit is in a separate structure which prevents aerated fork oil from entering the inner damper assembly & degrading its damping abilities
  • the inner damper is pressurized, it also eliminates bubbles forming in the oil
  • "Speed Sensitive" design means the damping force is controlled by piston speed, not position in the fork
  • low friction fork seals provide reduced stiction for a smoother stroke
  • spring & damping settings are optimized for cross country use
  • fork adjustments include: 20-way compression damping & 20-way rebound damping
  • optional fork springs are available through Genuine Yamaha parts
• Fork also features a Transfer Control Valve (TCV).
  • TCV enhances damping from mid to full stroke & improves bottoming characteristics
  • TCV offers more precise control throughout the full suspension stroke
  • TCV is located on the upside of the spring & 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 protection from dirt, mud & stone chips
  • "self-supporting" design reduces friction for smoother stroke
• Monocross link rear suspension features a fully adjustable, Kayaba, piggyback shock which provides 315 mm (12.4") of wheel travel.
  • features separate adjusters for high- and low-speed compression damping
  • adjustments include: spring preload, 20-way rebound damping, 20-way low-speed compression damping & 2 turns of high speed compression damping
  • spring & damping settings are optimized for cross country use
  • 18 mm damper rod
  • Kashima coating (friction reducer) is used in the shock body & sub tank to reduce friction & improve suspension performance
  • piggyback shock utilizes a full rebound oil lock system for excellent suspension function & great ride quality
  • spring & damping settings are optimized for cross country use
• 270 mm floating front "wave-style" disc brake with Nissin twin piston caliper.
  • "wave" style rotor (disc) reduces weight, improves cooling (more surface area) & improves styling
  • braking performance is excellent with great feel & control
• "Shorty" front brake lever is adjustable for various hand sizes.
• 245 mm rear "wave-style" disc brake with single piston caliper.
  • integrated master cylinder (fluid reservoir is integrated into the top of the master cylinder)
  • "wave" style rotor (disc) reduces weight, improves cooling (more surface area) & improves styling
  • strong stopping power with excellent feel & control
• Rugged, plastic rear caliper & lower rear disc protectors / guards.
• Lightweight, Sun Star rear sprocket.
  • increases the contact area between the sprocket & chain rollers
  • reduces the load on the chain & increases service life of chain & sprocket
• Heavy duty "O"- ring chain for excellent durability.
• Lightweight, D.I.D. 21" front and 18" rear rims & premium Dunlop tires.
  • provide excellent durability
  • reduces unsprung weight for optimal suspension performance & handling
• "Flat-design" seat features multi density foam.
  • provides good initial softness / comfort and then increases the firmness as more pressure is applied
  • "pebble" finish on the top and side surfaces provides excellent rider grip & durability
• Seat, handlebar & fuel tank ergonomics provide excellent freedom of movement for the rider.
• Large, 8 litre plastic resin fuel tank.
  • on - off - reserve fuel petcock
  • reserve amount is approx. 2 litres
• Lightweight aluminum side stand.

DETAILS

• Bold New YZ Styling
  • Along with the slimmer, more aggressive bodywork, a new front and rear fender design and new radiator shrouds all integrate with a bold new graphics scheme to highlight the YZ family pedigree. Premium Yamaha graphics are now embedded to provide excellent durability and scratch resistance.
• Slim design, aggressive bodywork allows easy rider movements
• Lightweight YZ250F/450F based wide footpegs provide excellent grip & ground clearance
• Rugged chain guide helps prevent the chain from de-railing and also helps to protect the rear sprocket.
• Serrated rear brake lever and folding shift lever tip
• Stainless steel, inner clutch cable provides excellent strength, smooth action and long life
• Heavy-duty 520 "O" ring chain
• E10 friendly fuel system components