Key performance
Technical specifications
- Displacement
- 124 cc → 125 cc
- Power
- 40.0 ch (29.4 kW) → 40.0 ch (24.5 kW)
- Compression ratio
- 8.6:1 → 10.7:1
- Lubrication
- Wet sump → Premix
- Starter
- — → Kick
- Frame
- semi double berceau → Semi-double cradle aluminium frame
- Clutch
- Multiplate, wet → Multiplate wet clutch
- Front suspension
- Speed-sensitive system inverted fork → KYB® Speed-Sensitive System inverted fork; fully adjustable
- Rear suspension
- Fully adjustable single shock → KYB® single shock; fully adjustable
- Front brakes
- Single disc. Hydraulic → Single disc. Hydraulic.
- Rear brakes
- Single disc. Hydraulic → Single disc. Hydraulic.
- Seat height
- 998.00 mm → 975.00 mm
- Ground clearance
- 386.00 mm → 366.00 mm
- Width
- — → 828.00 mm
- Height
- 1316.00 mm → 1295.00 mm
- Fuel capacity
- 7.95 L → 8.00 L
- Weight
- 94.40 kg → 93.90 kg
- New price
- 6 699 € → 7 499 €
Engine
- Displacement
- 125 cc
- Power
- 40.0 ch (24.5 kW)
- Engine type
- Single cylinder, two-stroke
- Cooling
- Liquid
- Compression ratio
- 10.7:1
- Bore × stroke
- 54.0 x 54.5 mm (2.1 x 2.1 inches)
- Fuel system
- Carburettor. Mikuni TMX 38
- Lubrication
- Premix
- Ignition
- CDI
- Starter
- Kick
Chassis
- Frame
- Semi-double cradle aluminium frame
- Gearbox
- 6-speed
- Final drive
- Chain (final drive)
- Clutch
- Multiplate wet clutch
- Front suspension
- KYB® Speed-Sensitive System inverted fork; fully adjustable
- Rear suspension
- KYB® single shock; fully adjustable
- Front wheel travel
- 300 mm (11.8 inches)
- Rear wheel travel
- 315 mm (12.4 inches)
Brakes
- Front brakes
- Single disc. Hydraulic.
- Rear brakes
- Single disc. Hydraulic.
- Front tyre
- 80/100-21
- Rear tyre
- 100/90-19
Dimensions
- Seat height
- 975.00 mm
- Wheelbase
- 1443.00 mm
- Ground clearance
- 366.00 mm
- Length
- 2136.00 mm
- Width
- 828.00 mm
- Height
- 1295.00 mm
- Fuel capacity
- 8.00 L
- Weight
- 93.90 kg
- New price
- 7 499 €
Overview
It’s a question that comes up often: is the Yamaha YZ125 automatic? No, and thankfully so. This track beast has nothing to do with a washing machine. It’s a true, hard-core competition motorcycle that demands commitment. For the 2019 model year, Yamaha mainly revised the graphics, leaving the essential mechanics unchanged since the major overhaul of 2015. We’re talking about a 125cc motocross bike that, for many, remains the benchmark for raw sensations and efficiency on a circuit.

Beneath its factory bike appearance, with its slender bodywork and aggressive Speed Block graphics, lies a heart that doesn’t lie: a 125cc two-stroke engine delivering 40 horsepower for just 94 kg fully fueled. These figures are immediately felt. The engine’s revving is electric, almost violent, and the lightness sticks you to the handlebars with feline agility. This is precisely the recipe that makes this Yamaha YZ125 dirt bike the perfect tool for ambitious young riders. It’s a school of agility, a necessary step to tame the power before considering, perhaps, a YZ250F. Its top speed, around 110 km/h, isn't the point; it's the explosiveness out of corners and the ease of launching that count.
The technical specifications are a catalog of serious parts. The 48 mm KYB inverted fork and the Monocross shock absorber, fully adjustable, are directly inherited from the YZ-F four-stroke models. They offer a direct transfer of high-end sensations, with traction and stability in the whoops that inspire incredible confidence. The braking, with its 270 mm front disc adopted in 2017, bites with precision. Everything, from the wide footpegs to the clutch free play adjustment knob, is designed for the track. This is far from a basic machine.

So, what is the price of this weapon? In 2019, it was listed at €7499. Today, for a new 2024 Yamaha YZ125, you’ll have to count on considerably more, probably around €9000. The used market, however, tells a different story. The value of an older model, such as a 1990 or 1993 in good condition, can be around $2700. It’s an accessible budget to taste the legend, especially since sites like CMSNL are full of parts to maintain these models, including collector’s editions like the 70th Anniversary.

Its real flaw? It’s uncompromising. This two-stroke demands technique, maintenance, and doesn’t forgive laziness. It is not homologated for road use; its kingdom is clay or dirt track. Faced with a KTM 125 SX, as light and lively, or a Suzuki RM125, the choice becomes a matter of feeling. But Yamaha has that certain something, a robustness and linearity in development that reassures. For those looking for the most accomplished and formative 125cc motocross bike, the one that has written history for decades, the YZ125 still commands respect. It’s a machine that hasn’t aged, because it has never sought to be anything other than a champion.
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