In the motorcycle industry, there’s a constant tug of war between passion and practicality. Sometimes passion wins, and that’s why the Yamaha YZ125X exists. No one in the accounting department demanded this bike. There was no tidal wave of demand for a 125cc off-road two-stroke and no computer model that suggested massive profits would result from its creation. This is a model driven by passion and pride. It was created by enthusiasts for enthusiasts.
WHY AND HOW
The 125 off-road two-stroke is a subcategory within a subcategory. While Honda, Suzuki and Kawasaki abandoned all full-size two-strokes 16 years ago, Yamaha actually expanded its offerings by pushing into the off-road market with the off-road X series. Some will point out that Yamaha hasn’t invested as much in new two-stroke technology as it has in four-strokes, but those same critics often reject new technology and the increase in price that comes with it.
Even though the tech is decidedly old-school, this motorcycle has massive changes for 2023. It is based on the YZ125 motocross bike, which had a long list of changes last year, and follows in those footsteps with a mostly new motor and completely new bodywork. The suspension is also updated just as the YZ125 motocross bike was. Comparing this motor to last year’s YZ125X would show that the crank, cylinder, cases, power valve and piston are all different. Compared to the current motocross version, there are a number of changes that make the X more suitable for off-road riding. The combustion chamber has a 7-percent increase in volume, and the compression ratio is either lower or higher, depending on the position of the power valve. When the power valve is closed, the corrected compression ratio is 10.21:1, which is a 5-percent reduction. With the power valve open, it’s 7.81:1, which is a 1-percent increase. The power-valve governor is also designed to open later. The ignition mapping is different, and the jetting is a touch leaner in most circuits.
The suspension is very similar to the motocross version’s right down to the spring rates, which are stiffer than those of last year’s X. The suspension is still softer at both ends compared to the MX bike, but that’s accomplished entirely through changes in the valving. Then there are the standard badges of offroad membership—an 18-inch rear wheel, a kickstand, a petcock with a reserve position, an O-ring chain and slightly lower final gearing in the rear (50-tooth versus 49). Things that are the same as the motocross bike include the fuel capacity, the gearbox, the pipe and the silencer.
It’s hard not to love this bike. It’s like an emotional support animal that doesn’t require a pooper scooper. Having a bad day? Do a few laps on the X. Had a fight with your girlfriend/boyfriend/mom/dad? Hit your favorite trail and you will feel better. The YZ125X is preposterously easy to ride, and it’s easy to believe it’s all you. You’re stronger, more skillful and more physically fit aboard the YZ125X.
Objectively speaking, this is because the bike is light and has outstanding suspension at both ends. The YZ125X actually gained a little weight this year, but it’s still absurdly light at 206 pounds. Going from a modern four-stroke motocross bike to this is akin to doing high jumps on the moon. The fork is essentially the same as that of the current YZ250F, although the settings are softer and the axle carriers are different to accommodate a smaller front axle. The shock is completely different because it’s designed to fit the central backbone aluminum frame that was the Yamaha norm in the mid 2000s. That doesn’t matter, though. The suspension is outstanding, just like it is on all the Yamaha off-road models. It’s probably best for an adult off-road rider who weighs over 150 pounds. That’s an odd target considering the stereotypical 125 rider is in his teens. That rider might actually like the X on a motocross track, where the standard YZ125 is a little on the stiff side. We really don’t expect Yamaha to know exactly which rider is going to end up with this bike, but it’s a remarkably good compromise. That’s a hallmark of good suspension design.
Another reason the YZ125X is such a hero-maker is because of its overall power output, which is modest by modern standards. It has less peak power than the motocross version, which has less peak power than any of the Austrian 125s. Low-end power, on the other hand, is much stronger on the X. That’s especially welcome because the new motor in last year’s YZ125 is more demanding compared to the previous model. It gained on top, but surrendered a little too much down low. The X has recovered that low-end power and more. That makes the bike even easier to ride. When you fall off the powerband, it’s no big deal. You can hurry the recovery process with a quick dab on the clutch or wait for the motor to pull itself back into a happy zone, which it will do. On the other end, the X revs to about the same rpm level as a typical 125 two-stroke, but you never get a super-strong hit. The most significant change for this year’s YZ125X is in ergonomics. It’s a sleeker, more modern-feeling bike than ever before. The transition from seat to tank is more level, and the overall feel isn’t that different from that of a contemporary four-stroke. Along the way, the YZ125X gained a little seat height.
After years without real change in the 125 two-stroke world, we’ve seen a lot happen quickly. The KTM and Husky 125s have new motors with throttle-body fuel injection. They have considerably more low-end than older KTMs and Husky 125s, but not as much on top. That gives new life to both the Yamaha 125s, which suddenly find themselves more competitive in the power game.
Still, the YZ125X’s main focus isn’t high-level racing. It’s an off-road play bike or perhaps a transition bike for a young motocross rider moving up from a mini. It remains one of the best-handling dirt bikes in the world, with hero-making suspension, a forgiving power delivery and proven reliability. From a standpoint of making smiles and having fun, that’s a formula that’s unbeatable.