Yamaha YZ125 2018 — Specifications

Do you remember the first time you heard the scream of a two-stroke on the track? That sharp, almost electric sound, announcing a mechanical fury far more impressive than its simple dashboard. The Yamaha YZ125, in its 2018 version, is the very embodiment of this tradition. This isn't a bike for riding around the lake; it's a pure competition weapon, a brutal learning tool for ambitious young riders. With only 93.9 kg to feed its 40 horsepower, it offers a power density that makes many larger four-strokes blush. We are talking about the most performant 125cc motocross bike ever produced by the Japanese manufacturer, a title it has defended for decades, with a lineage dating back to at least the 1982 models, the parts of which are still sought after by collectors.

On paper, the figures seem modest. But on a bumpy terrain, it's a different story. This two-stroke single-cylinder, with its 54 mm bore and YPVS system, is not a brute force engine. It requires technique, commitment, knowing how to hold it in the redline to extract all its velocity. It is precisely this demand that forges future champions. It serves as a compulsory, and often indelible, stepping stone before climbing onto a YZ250F or a 450F. The six-speed gearbox with close ratios, the responsive 38 mm carburetor, everything is calibrated for the track. Top speed? Approximately 110 km/h, sufficient to dominate a straight section on a motocross circuit, but the real game is played in acceleration and pickup.

Compared to its direct rivals, the YZ125 occupies a particular place. The KTM 125 SX is perhaps more nervous, the Suzuki RM125 has its character, but the Yamaha has this solidity, this obviousness of operation that inspires confidence. Its semi-double cradle aluminum frame, its fully adjustable KYB suspension – an inverted 48 mm fork and a single shock at the rear – offer a remarkable balance. Improvements since 2015, such as the front brake moved to 270 mm or the wide YZ-F style footrests, are touches that refine the experience without revolutionizing the formula. The price of 7499 euros for this 2018 version provides a reference; for the 2024 or even the future 2025 models announced, such as the possible Monster Energy, you should expect an increase. Generally speaking, the market for older bikes is also active: a 1990 or 1993 YZ125 in good condition can be negotiated around $2700, a testament to its durability.

Is it a bike for everyone? Absolutely not. It is strict, sharp, and is not homologated for the road. It requires total commitment, meticulous maintenance, and a passion for high-frequency mechanics. But for a young track rider wanting to learn the true lessons of riding, where every engine misjudgment is immediately paid for, it remains an undeniable master. Yamaha, while celebrating its 70th anniversary, does not need to reinvent this YZ125. It just needs to continue building it, because it is already, for a long time, a legend in action.