2018 Yamaha YZ125 Long Term Update

15 Hours And Counting…

After our first rides on Yamaha’s YZ250 and YZ125, I’ve had the pleasure of riding the small bore around SoCal tracks for the last two months and I’ve had a smile on my face the entire time! Two-strokes are making a comeback in the motocross world and the off-road scene is flooded with them in both the 125cc and 250cc classes and for good reason. They’re fun, reliable, and relatively cheap – who wouldn’t want that? We forgot to mention the sweet smell of Maxima 927 in the morning is tough to beat as well! Being the smaller rider that I am, I fit the little YZ well and the fun factor of riding this bike – especially at faster tracks like Cahuilla Creek MX and Glen Helen Raceway – is unparalleled. The lightweight feeling and agileness of the bike paired with a screaming motor just to barely downside a jump makes you feel like a hero even if you aren’t going all that fast.

The small bore YZ makes the easiest of jumps a little harder but a lot more fun!
Smiles for miles when aboard Yamaha’s 125cc two-smoker!

The YZ hasn’t had any major updates in the past decade so it’s already a proven bike with years to refine the motor, suspension, etc. and we are reaping the benefits. A big debate between four-stroke and two-stroke riders is the maintenance schedules and affordability of owning each bike. Well, with close to 15 hours on the bike, the maintenance has been fairly straight forward. I try to change the oil every 5-6 hours using Maxima’s MTL XL 75wt transmission fluid as I have had good luck with running it in my own personal 125 in the past.

Maxima has kept the little YZ running strong and stopping fast.
We bled the rear brakes fairly early on the pads are now coming to the end of their life.

Additionally, we bled the brakes fairly early on using Maxima’s Racing Dot 4 Brake Fluid just to be sure. Additionally, we clean the air filter after every ride to keep maximum air flow and to prevent any risk of sucking dirt into the motor. Finally, a Maxxis Maxxcross SI rear tire was thrown on after the stock MX52 finally wore out. The stock chain and sprockets are still looking halfway decent but we are getting to the point where we have to adjust the chain almost every ride. Additionally, we use Maxima Chain Guard to lube the chain which we previously wrote about the benefits of using Maxima’s chain lube.

The suspension and engine on the YZ are hard to beat with minimal adjustments.

The OEM grips are as good as new (though not the most comfortable or forgiving on the hands). We’ve been running 91 pump gas with Maxima 927 premix and haven’t had any issues as of yet; although, we aren’t expecting any due to Yamaha’s proven durability and our past experiences. We’ve messed around with the suspension a bit and are really comfortable with how the bike worked in stock trim. Running 105mm of sag, we have sped up the rebound 1 click and stiffened up the compression two clicks in the fork to get rid of the initial harshness but still maintain bottoming resistance. Additionally, we slowed down the rebound 2 clicks and stiffened up the low-speed compression two clicks in the shock.

The YZ125 powerplant is virtually bulletproof.

With 4 years of off-road racing experience on a YZ125, I’ve spent my fair share of time working on one and seeing what wears and what doesn’t. Riding a 125 requires the majority of the time to be spent in the higher RPM’s which induces wear much quicker. As a precaution, we would always change out the piston/ring around 20 hard race hours. More often than not, we could’ve gone much longer but with the ease of working on the bike and the relatively low cost of rebuilding the top end, it was better to be safe than sorry. We have seen up to 35-40 hours on a YZ125 top end but that’s stretching it a bit far and we wouldn’t recommend prolonging standard maintenance that long. We’ll continue to put Yamaha’s YZ125 through its proper testing and continue to provide updates in the near future so stay tuned!

The stock chain and sprockets are beginning to show their signs of wear.
The stock Dunlop MX52’s are more than durable as we are still running the front tire confidently.

Take a couple laps around Glen Helen Raceway on the YZ125 with Trevor Hunter!