RIDING THE 2024 YAMAHA YZ125X & YZ250X: TWO-STROKE TUESDAY
Some motorcycles owe their entire existence to passion. For Yamaha, that’s the real reason behind the YZ250X and YZ125X. There’s very little profit motive here; Yamaha already owns the market for Japanese two-strokes. For every X-model they sell, there’s probably one less MX model sold. It doesn’t matter. Yamaha is run by people, and luckily for us, there’s enough passion and enthusiasm in the hearts of those people to keep Yamaha in the two-stroke off-road game. When we went to Union, South Carolina, to test the brand-new YZ450FX four-stroke, we also got to ride the not-so-new two-stroke X-models, and it rekindled the passion we have for those bikes.
YAMAHA YZ250X
The YZ250X has only existed since 2016. That’s a little misleading, though, because we all know that the YZ250 motor dates back to 1999 with infrequent modifications. The aluminum central-backbone frame first appeared in 2005. In 2016, however, Yamaha took the motocross bike and gave it an off-road makeover. Then, a year ago, it got a big update with new bodywork and suspension upgrades.
Yamaha knows that riders routinely modify the motocross version of the YZ250 for off-road. The aftermarket supports that with larger fuel tanks, handguards, bolt-on kickstands and so forth. There are certain things that the average joe can’t do in his garage, though, and that’s what Yamaha concentrated on with the YZ250X. The gearbox was number one on that list. The X has a wide-ratio 5-speed. First and second gears are the same, but third, fourth and fifth are progressively taller.
The Yamaha YZ250X got new bodywork and a fresh outlook last year.
There are numerous changes that affect the X’s power delivery. The cylinder head volume is increased, the compression ratio reduced and the exhaust port raised. The power-valve shape and timing are altered, along with the ignition mapping. The clutch plates are made of different material, and the expansion chamber is tucked up tighter and out of harm’s way. The X uses the same fork as the MX model, but with softer valving and softer springs (4.3 N/mm versus 4.4). The same is true of the shock (48 N/mm versus 50). From there, it’s just bolt-on stuff: an O-ring chain, an 18-inch rear wheel and a kickstand. The YZ250X has the same fuel tank as the MX version (1.8 gallons) and the same silencer.
The YZ250X still has an aggressive hit despite everything Yamaha did to tame it down. It’s still more race bike than trail bike.
If you expect all that to transform the fundamental nature of the YZ, it doesn’t. The YZ250X runs, handles and behaves like a current YZ250, albeit a modified one. All those alterations make life a little easier in many off-road situations, but the YZ is still a YZ. That means it’s a race bike at its core. That’s wonderful news for riders in many venues like the NGPC series, which pits all 250s in the same class whether they are two-strokes or not. In a head-to-head race with any 250F, the YZ250X has an advantage in peak horsepower and a slight advantage in weight. It makes about 2 or 3 more peak horsepower than the newest YZ250F and weighs about 3 pounds less.
If you compare suspension, handling and manageability, the four-strokes have an advantage—that shouldn’t surprise anyone. The YZ250X hits hard and signs off early. Even compared to other off-road two-strokes, the Yamaha is a bit of a handful. All the tweaks and adjustments to the YZ250X make it smoother in the middle of the powerband, but it’s a bike that requires aggression and commitment if you go racing. You can, however, take it down a notch and ride the X just below the big power surge all day long. It’s hard to stall and makes excellent torque.
Another trait that shouldn’t surprise anyone is the suspension, which is excellent. The X isn’t far from the current YZ four-stroke suspension, which is still considered tops in the motocross world. It’s softer than the MX spec, but for most off-road riders, it could be softer still. Yamaha is still thinking of racing. It’s probably hard to get out of that habit.
YAMAHA YZ125X
The 125 world recently tipped on its axis. Prior to 2022, the Yamaha YZ125 motocross bike had been considered a relic of a bygone era. It handled extremely well, but the motor gave away too much to the KTM/Husky/GasGas gang of three. Then, the YZ125 got a new motor, new bodywork and updated suspension. Now it’s back in the hunt. But, weirdly enough, it has little to do with the new motor and the other updates. A new world order was sparked when all the Austrian 125s were redesigned with an ultra-complex array of electronic features. As a result, the House of Austria is now in disarray.
The YZ125X regained its crown as the lightest off-road race bike you can buy. It still weighs 206 pounds without fuel, but other bikes in its class recently gained weight (and electric start).
In the meantime, the Yamaha YZ125X got all the same updates that the motocross version received in 2022. Even though the YZ motor doesn’t look much different, it has new cases, a new top end and a new Keihin Power Jet carb replacing the old Mikuni. It also has a Moto Tassinari reed block as standard equipment. In order to differentiate it from the motocross model, the X gets most of the same alterations as the 250X: a different head and cylinder, different mapping and different carb specs. It didn’t get any change to the gearbox because the YZ125 already had a 6-speed. The suspension also got the off-road treatment, but in this case, it didn’t include a reduction in spring rates. Only the valving is changed. The final ingredients are the O-ring chain, the 18-inch rear wheel and the kickstand.
The YZ125X is hero material on the trail. The bike is insanely light and might well be the best-handling bike there is. It’s a blank check when it comes to riding over your head and getting away with it. The new bodywork makes it feel much more streamlined and modern, but it did result in a slightly taller saddle height. Normal-sized riders don’t notice, but it might be a factor for teens. The suspension might also be tuned for adults rather than kids. It’s great if you’re over 150 pounds, but kind of stiff otherwise.
There’s a lot of history on display here. The YZ two-stroke motor can trace its genesis back to 1999. The frame came in 2005 and the first generation of the SSS KYB fork came in 2007.
In the 125 horsepower wars, nothing exists in a vacuum. The new version of the YZ125X has only the slightest improvement in peak power over the previous one. The redesigned motor might have been considered a flop if not for one thing: it’s just as fast as the newest version of the KTM 125XC. That bike gained weight and lost peak horsepower when it went to throttle-body fuel injection and electric start. We believe that the KTM motor still makes more low-end power, but without one for a direct comparison in South Carolina, we can’t say how much. KTM also has the 150XC-W in this broad category, but it prices itself out of the YZ125X’s class ($10,099 for the KTM, $7199 for the Yamaha).
The YZ125 emerges as one of our very favorite off-road bikes, just based on pure fun factor. We have no problem with the carburetor, the kickstarter or the fact that you have to turn off the fuel petcock when you’re done. The sound of the motor continues to make us smile every time we hear it. Some things never change.
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