Conquer Dirt
Lightweight, quick and easy to maintain, the YZ125 is a perfect transition bike for those too big for 85s but too small or inexperienced for bigger, more powerful four-strokes.

Performance
Ceramic composite cylinder bore is a liner-less design with the ceramic coating sprayed directly on the aluminum block. The benefits include reduced weight (no heavy iron liner), reduced friction, extended cylinder life and excellent heat dissipation for consistent power delivery.

• Liquid-cooled, 124cc, crankcase reed valve-inducted 2-stroke engine provides class leading power & acceleration.
  • super crisp, instant "right now" engine power (when in the "power band")
  • easy & economical to maintain, service & rebuild
• 7.5-degree cylinder angle & straight shot intake path through the combustion chamber.
  • maximum power output
• Ceramic composite cylinder bore is a "liner less" design with the ceramic coating sprayed directly on the aluminum block.
  • reduced weight (no heavy iron liner)
  • reduced friction
  • extended cylinder life
  • excellent heat dissipation for consistent power delivery
• Specially designed combustion chamber achieves a more complete burn at higher rpm.
  • class leading power
• Lightweight, flat top forged aluminum piston.
  • excellent durability
  • light weight means fast engine response
  • matches combustion chamber design for maximum power delivery
• Lightweight, ball bearing style crank.
  • lightweight design for fast throttle response
  • friction reducing crank seals
• Compact crankcases.
  • lightweight design
  • helps centralize mass
• Quick-access, magnesium outer (sub) clutch cover.
  • light weight design
  • speeds clutch access
• Close-ratio, 6-speed transmission uses optimized gear ratios.
  • 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
• Yamaha's patented YPVS system.
  • features a slide (guillotine) type power valve that provides the benefits of both solid, low-rpm power delivery combined with a strong top-end punch. This system varies the exhaust port height and timing based on engine rpm.
• Mikuni TMXx38 carburetor features a "D" slide design.
  • enhances overall power delivery
  • provides crisp throttle response at all rpms
• 6-petal, carbon fiber reed design.
  • for stronger high-rpm performance with greater over-rev capacity
• 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 features a re-packable aluminum silencer which allows the rider / tuner to maintain the correct amount of back pressure for maximum engine performance while reducing noise.
• Works-style clutch lever & race-spec "barrel adjuster."
  • easy lever pull
  • for on-the-fly clutch adjustments

• 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 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 300mm (11.8").
  • fork adjustments include: 20-way compression damping & 20-way rebound damping
  • optional fork springs are available through Genuine Yamaha parts
  • low friction fork seals provide reduced stiction for a smoother stroke
  • 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
• 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 315mm (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
  • 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.
• 270 mm floating front 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.
• 245mm rear 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.
• "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
• Lightweight, D.I.D. 21" front and 19" 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.