The YZ125 might be the most popular motocross bike on earth. After 42 years it lives on, which means Yamaha must be doing something right. To this day it’s a relevant bike that fills a niche in the dirt bike world. We’ve complied a list of 10 important YZ125 facts that you might or might not know.
1The Yamaha YZ125 has had the longest production run of any MX bike in the world. The YZ125 has been in Yamaha’s line since 1974. The only other bike that can make a similar claim is the Yamaha YZ250 two-stroke. It might be said that the 2016 YZ125 is nothing like the original bike of the ’70s, but it was the same model with the same purpose and had the same name. Yamaha doesn’t tell us the actual number of bikes made over the last 42 years, but most pundits agree that the YZ125’s numbers make it the most popular MX bike in the world over the long run.

2The Yamaha YZ125 is the only surviving Japanese 125. It’s no secret that Suzuki, Honda and Kawasaki stopped making 125s in the mid-2000s. It wasn’t because of some massive conspiracy to kill the two-stroke. In truth, it was because the YZ125 killed them. In order to make a bike as good, the other Japanese manufacturers would have had to invest major resources in the project, and the market wasn’t big enough for everyone.
3The Yamaha YZ125 has only a few changes for 2016. The rims are now black. The chain is gold, and there is minor suspension re-valving. In 2015, however, the little YZ got a number of changes. The new bodywork was obvious, but there were also significant changes to the suspension. It got the same KYB SSS fork that’s supplied to the YZ250F and YZ450F, but with different spring and damping values. The axle lugs are also different from those of the four-stroke models to accept a smaller front axle.


4The Yamaha YZ125 is the best-handling dirt bike in the world. At least we think so. Handling is such a broad term that it can mean almost anything, but when you ride the YZ125, there’s no other word that describes what the little bike does so well. It’s easy to ride and, more than anything else, it’s extremely forgiving. Never mind all the talk about how hard it is to keep a 125 on the pipe. That’s a talent that can be picked up or remembered very quickly. The bike has some of the most sophisticated suspension in the world and it’s very, very light. What could go wrong?
5The Yamaha YZ125 is super light. How light is it? On the fabulous Dirt Bike Nuclear Scale, the YZ weighs 200 pounds without fuel. You might have expected a smaller number based on years of misinformation and advertising hype. Over the years, Yamaha has claimed dry-weight figures that were, to be blunt, made up—usually around 190 pounds. More recently, the company has provided wet-weight figures that are closer to reality. For comparison, the 2016 YZ250F weighs 222 pounds on the Dirt Bike scale. The YZ450F is 239 pounds. We haven’t yet weighed the new KTM 125SX, but we expect it to be lighter than the YZ125.


6The Yamaha YZ125 makes 35 horsepower. A YZ250F four-stroke is around 38 horsepower, which means that the 125 has a power-to-weight ratio that’s 2 percent better. Does that mean it can out-accelerate a 250F? No. When you add riders of equal weight, the picture changes. With 150 pounds of rider and fuel on each bike, the 250 is 2 percent better. So much for numbers. There’s also the matter of the powerband. The 250F makes more power over a longer range, which can be a big advantage. But still, you get the overall picture. A YZ125 makes peak power that is at least in the ballpark.
7The Yamaha YZ125 can be made more powerful. Yamaha sells a 144cc kit through Genuine Yamaha Technology Racing. It’s actually made by Athena, and it boosts the YZ to nearly 40 horsepower. It makes the bike more competitive on the track, but perhaps at the cost of friendliness. The YZ144 doesn’t rev as high, vibrates more and is a little harder to start.


8The Yamaha YZ125 is a great transition bike. If you have a young rider graduating from 85s, the 125 is actually a great choice because he already knows how to keep a two-stroke singing.
9The Yamaha YZ125 can be rebuilt for $100—that’s the price of a piston, ring and gaskets. The same parts on a 250F cost a little more, but stock valves will cost an additional $300 and a cam chain is $25. If you need cams, that’s another $300. On the flip side, you need to replace the 125 top end about twice as often. Maybe three times as often. It’s a good thing it’s a quick job.
10The Yamaha YZ125 sells for $6390, whereas a YZ250F is $7590. MSRP is $6899 for a Husqvarna TC125, $6799 for the KTM 125SX and $6899 for the KTM 150SX. There’s also a TM 125MX for $8150 and a 144 for $8400.
Those are 10 good reasons the Yamaha YZ125 isn’t going away. Yes, it has a hard time competing with a 250F; that’s not news to anyone. But, it isn’t a 250F. It’s a 125, and it has its own personality with advantages and disadvantages. It’s also the most inexpensive full-size MX bike you can buy and race today. And did we mention the part about it being the best-handling bike in the world? It’s a fact worth repeating.

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