Built around Yamaha's cross - motocross motorcycle platform, the 2015 Yamaha YZ125 pairs a 124 cc (7.6 cu in) liquid-cooled single cylinder, two-stroke architecture with road-focused gearing. Internal engine geometry specifies a bore and stroke of 54.0 x 54.5 mm (2.1 x 2.1 inches) with a 8.6:1 compression ratio.
On the scales, the YZ125 measures 94.8 kg (209 lbs) wet (curb). Rider ergonomics and chassis geometry center around a 975 mm (38.4 in) seat height — reflecting a long-travel chassis stance that favors ground clearance and off-pavement control, combined with a 1,443 mm (56.8 in) wheelbase engineered for balanced agility and highway composure. The 7.95-liter (2.1 US gal) fuel tank supports practical everyday commuting and weekend road stints.
Within MotoLibrary's Yamaha archive, this model family spans 19 indexed model years from 2008 to 2026, allowing buyers to track year-over-year changes in emissions tuning, weight and equipment.
Standover Height
975 mm (38.4 in)
Engine
Displacement124.0 ccm (7.57 cubic inches)
Engine TypeSingle cylinder, two-stroke
Engine DetailsReed-valve-inducted
Compression8.6:1
Bore x Stroke54.0 x 54.5 mm (2.1 x 2.1 inches)
Fuel SystemCarburettor. Mikuni TMX 38
IgnitionCDI
CoolingLiquid
Transmission
Gearbox6-speed
Final DriveChain (final drive)
Chassis
Frame TypeAluminum
Rake28.0°
Front SuspensionSpeed-sensitive system inverted fork
Front Travel300 mm (11.8 inches)
Rear SuspensionFully adjustable single shock
Rear Travel315 mm (12.4 inches)
Wheelbase1443 mm (56.8 inches)
Ground Clearance366 mm (14.4 inches)
Wheels & Brakes
Front Tyre80/100-21
Rear Tyre100/90-19
Front BrakesSingle disc. Hydraulic.
Front Brake Ø250 mm (9.8 inches)
Rear BrakesSingle disc. Hydraulic.
Rear Brake Ø245 mm (9.6 inches)
Dimensions & Weight
Weight incl.94.8 kg (209.0 pounds)
Seat Height975 mm (38.4 inches) If adjustable, lowest setting.
Use this page to compare this motorcycle by its real specifications, not only by model name. Focus on the details that affect fit, comfort, handling, range and ownership.
Seat Height
Check the seat height against your inseam and riding posture before choosing a motorcycle.
Fuel Capacity
Fuel capacity helps estimate touring range and how often you may need to stop.
Brakes
Brake setup is worth comparing if you ride in traffic, mountains or with a passenger.
Suspension
Suspension details can matter for comfort, road feel and long-distance riding.
Transmission
Transmission and final drive affect maintenance, smoothness and everyday usability.
