The carburetor has been completely redesigned! We explain the latest technology behind Yamaha’s new 2026 YZ125 motocross bike.

The YZ125 occupies a special place in Yamaha’s off-road lineup. Lightweight and easy to handle, it’s the perfect first step for young riders entering the world of motocross. It’s also a reliable companion for experienced riders looking to purely enjoy two-stroke riding. The 2026 model further unleashes that potential, evolving into a machine that can be easily controlled “anytime, anywhere, by anyone.”

New carburetor and ignition system – for even easier handling

The development of the new YZ125 focused on improving the carburetor and CDI.

By changing the shape of the intake path and optimizing the ignition timing, a seamless power feel is achieved from low to high speeds. The smoothness when exiting corners is particularly noticeable, allowing the rider to freely draw the intended line.

Changes to the power jet and float height have also improved response when opening the throttle suddenly. The output characteristics are more powerful and easier to handle than before, making it a machine that even entry-level riders can attack with confidence.

Resistant to environmental changes – seasonal settings

Another appealing feature of the YZ125 is the ease of carburetor setting. Issues with the previous model included a sluggish response when opening the throttle suddenly and difficulty in setting the engine when temperature or altitude changed. To solve these issues, the carburetor’s main jet was enlarged from 160 to 178, increasing the amount of fuel supplied. This improved combustion stability across the entire rev range, and increased power especially at high rpm.

The needle has been changed from the previous specification to a thicker, two-stage tapered model (N3EW-2). This allows for cleaner combustion at low and medium throttle openings, and smoother transitions and more powerful characteristics at mid-to-high throttle openings. The pilot jet has been changed from 75 to 65, improving ease of handling from idle to low speeds. The air screw has also been changed from the previous 2 5/8 turns to 1 3/8 turns, resulting in more stable fuel mixture.

The power jet has been significantly enlarged from 35 to 95, improving fuel supply when opening the throttle suddenly. This also improves response. The float oil level has also been raised by 1mm compared to the previous model, further improving the stability of fuel supply.

The 178mm main jet is used in winter and spring/autumn, and the 172mm in summer, allowing for variations in temperature and humidity. The factory-installed main jets include 172mm, 175mm, 180mm, and 182mm, allowing riders to choose the optimal setting for their bike. The N3CW needle and 62/68mm pilot jets are also included, allowing for a wide range of adjustments.

These changes have given the YZ125 linear and smooth power output characteristics from low to high speeds. The behavior when exiting corners has become particularly smooth, giving greater freedom in line selection. The peace of mind that comes from being able to ride stably even when the weather or course conditions change is a major benefit even for amateur riders.

Appeal from a rider’s perspective

When listening to the feedback from riders who have test-ridden the bike, many have commented that it is “light and moves exactly as you want” and “gives you great freedom in corners.” In addition to the lightness that is characteristic of two-strokes, the 2026 model has more stable power output characteristics, making it enjoyable for a wider range of riders. Veteran riders have also commented that it is “perfect for practice,” making it clear that it is a valuable bike for everyone, from beginners to experts.

Yamaha has positioned the YZ125 as the foundation for developing the next generation of riders. Through support in amateur races and the BLU CRU Academy, the company has created an environment where young riders can step up their game. In fact, there are many riders who started their careers on the YZ125 and then went on to compete on the world stage on the YZ250 or YZ450F.

Young riders from Japan will compete in the 2025 BLU CRU Cup SuperFinale and perform on the international stage. The YZ125 is more than just a bike; it is a key to unlocking the future for young people pursuing their dreams.

A partner to support your growth

The new YZ125 has been designed with revised carburetor and ignition to maximize ease of handling and is versatile enough to withstand changing environmental conditions. It is a bike that will serve as a stepping stone for young riders to advance, and a way for veteran riders to fully enjoy the joy of 2-strokes.

Yamaha’s philosophy is that “anyone can be a winner.” The YZ125 embodies that philosophy. The 2026 YZ125 is a machine that will nurture future champions and at the same time bring smiles to the faces of all off-road fans.