First Impression: 2020 Yamaha YZ125X

A New Recipe For The Woods

Story by Trevor Hunter, Photos by Trevor Hunter/Ryan Nitzen

Yamaha introduced a new two-stroke model to their mix in the 2020 YZ125X and we were finally able to stir up the dirt on one last week. Yamaha invited us out to South Carolina, similar to last year, to unveil the YZ125X and all new YZ250FX at Randy Hawkins’ ranch in Union, SC. Utilized as the AmPro Yamaha team’s testing grounds and only a handful of miles from the Big Buck GNCC, the facility offered a real life testing experience on terrain similar to a GNCC and National Enduro since these bikes are built around that style of riding/racing. 

The YZX powerplant is similar to the YZ, but different enough to suit the trail conditions.

Many riders and racers often get in over their heads looking to make their bike more “off-road ready”, though the manufacturers err on the side of mixing up an existing dish with only a handful of key ingredients to transform one machine into an off-road racer. The chefs at Yamaha followed this recipe in creating the YZ125X, based off of the popular YZ125 motocross bike, and lessons learned with the successful YZ250X– it only boasts key features to prevail in the off-road terrain.

The YZX has a different feel out on the trail, and we’d say it is in the right direction.

The biggest change inside the engine: cylinder head is modified to raise the gap to the spark plug by 3mm, along with lowering the compression ratio from 8.6:1 to 7.4:1. Additionally, the bLU cRU altered the power valve shape, which acts as a way to lower the exhaust port without changing the cylinder, while timing it to open slower and later than on the moto bike. The CDI is also model specific with the 125X. All of this is claimed to smooth out the power curve making it easier to ride in tight terrain. The transmission and pipe/silencer is identical to that of the moto bike. Additionally, the jetting is slightly changed and the bike regeared to 13/50 instead of 13/48 to suit the east coast riding style. On the handling side of things, the suspension valving is changed, though the spring rates remain the same as the YZ125. Traditional off-road features include and 18 inch rear wheel (with a 18×2.15 inch rim rather than a 1.85), reserve fuel petcock, o-ring chain, and kick stand, though no handgaurds, oversize tank, or skid plate comes stock.

How do these changes stack up once the bike gets going? Yamaha is headed in the right direction with their new two-stroke model. The 125X did everything we had hoped for, from the motor to the suspension and handling. Right off the bat, the X is much easier to ride than its motocross brother. The bottom end is smooth and torquey for a 125  making this bike more capable in the tight singletrack. It is more willing to pull you through the tight trees smoothly and efficiently with less clutch than expected. It doesn’t have the hit like a YZ does, but it transitions well into the mid-top end where the bike makes most of its power. Overall, it has a slower revving characteristic and it may not be quite as exciting (it is a 125cc two-stroke so the fun factor is still up there), but it is more usable and efficient in the GNCC setting. The transmission worked well for us and the larger 50T rear sprocket was nice to have in the gnarlier portions of the trails. 

A larger rear sprocket, 18 inch rear wheel, and kickstand adorn the YZ125X.

The added torque made it easier to recover from mistakes as the bike didn’t fall on its face as much when in too high of a gear like a typical 125cc two-stroke. This proved beneficial in the trees if we’d come into a corner too hot or get caught off-guard and need a little boost to get back up to speed. Additionally, the refined motor characteristic makes this bike more appealing to a wider variety of riders, even if based in faster terrain like we see on the west coast. Those who aren’t quite aggressive enough to keep a 125 in the meat of the power would have an easier time riding the X model, along with those transitioning off of mini bikes who don’t want/need a pipey 125cc two-stroke fire breather underneath them. 

The 125X surprised us with how torquey and strong the bottom end was for a 125cc two-stroke.

On the suspension side of things, the YZX handled the trees and roots very well. We started with about 110mm of sag (after we caked on quite a few pounds of mud upon leaving camp), then worked our way back down to 107mm. This gave us a little more front end traction and helped in all of the quick and tight turns through the trees, whereas the front end was a little vague and would dance around the chop at 110mm of sag. After that, we never felt the need to touch a clicker with our 157lb frame aboard the YZ.

More often than not, manufactures’ off-road models are too soft for our typical fast conditions on the west coast simply because they are designed for this slower east coast terrain. However, now that we’re in the terrain the bike was really intended for, we can say we’re quite pleased with the suspension performance. It soaked up all of the little chop and square edges coming out of the corners keeping the rear end planted and driving forward. There were a couple instances where we’d bottom pretty good on hard, moto style impacts, but they were few and far between and we didn’t feel the need to sacrifice the performance in the tight terrain for the minimal hard jump landings.

Handling wise, the YZ125X is light and nimble just as we’d expect. Yamaha didn’t really add any weight to the bike so we weren’t expecting much of a difference there, but the same sensations transferred from the moto tracks to the woods. The bike is narrow and easy to maneuver and is almost too light-feeling after riding it back to back with a 250F. The 125 has the potential to bounce off of roots and rocks (deflect) a little easier if you hit it wrong whereas the 250F was more planted at all times. However, in the really tight, NEPG style terrain, the two-smoker was ideal for weaving in and out of trees without snagging the bars. The difference in weight between those two bikes is noticeable whereas we could’ve sworn the 250FX had wider handlebars on it. 

Overall, Yamaha’s 2020 YZ125X is a solid platform for a woods racer/rider. The fun factor alone of singing a 125cc two-stroke through the woods has us sold, and Yamaha’s changes to transfer it over into the off-road arena leave this bike as a serious competitor. An easier-to-ride motor package paired with plush suspension is the recipe for a race winner and is just awaiting the right chef to finish the meal. Give us a set of handguards, a skid plate, and an oversized tank, and we’ll be off to the races without skipping a beat!

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