We rode the new Yamaha YZ125X off-road two-stroke for the first time this week. This motorcycle has massive changes for 2023. It is based on the YZ125 motocross bike which had massive changes last year, so it 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. The fact that this bike even exists is a big win for us. It’s hard to imagine how that even came about. There’s no big demand for 125cc off-road bikes in the U.S.–never has been. There’s certainly a very loud base of cranky two-stroke fans, but they are notorious for being more talk than action. Still, those guys are right! All 125 two-strokes are wonderful bikes. This one especially.

Mark Tilley on the Yamaha YZ125X.

Comparing this motor to last year’s YZ125X would show that the crank, cylinder, cases, power valve and piston are all different. Those changes came to the motocross version a year earlier. In order to make that motor suitable for off-road riding there are a handful of further changes. The combustion chamber has a 7% increase in volume and the compression ratio is different. It’s 10.21:1 when the reshaped power valve is closed, which is a 5% reduction. With the power valve open, it’s 7.81:1, which is a 1% increase. The power valve governor is also designed to open sooner. The ignition mapping is different and the jetting is a touch leaner in most zones.

The 2023 Yamaha YZ125X has a MRRP of $7099.

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 valving is softer at both ends compared to that of the MX bike. Then there are the standard badges of off-road 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.

The best aspect of the YZ125X is that it’s preposterously easy to ride. It’s light and has outstanding suspension at both ends. That shouldn’t surprise anyone. The Yamaha X bikes generally have the best suspension in the off-road world. The YZ125X also has considerably more low-end power than the motocross version. That’s especially good because the MX bike lost a little low-end with the new motor last year. The X regained that and more. On top, the X might suffer a little. It’s not as fast as the MX bike, which isn’t quite as fast as the Austrian 125 two-strokes. This year represents a big shift in the 125 class as a whole, though. 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. The GasGas oddly enough, is now the top-end power king simply because it uses the older carbureted motor. We will have a full test of the 2023 Yamaha YZ125X in the August, 2024 print edition of Dirt Bike.


Rick “Super Hunky” Sieman served two stints as the Editor of Dirt Bike Magazine. He helped shape motorcycle journalism as we know it today and was instrumental in making Dirt Bike the icon that it is. Todd Huffman (of The Motocross Files) has been spear-heading an effort to get Rick on the AMA Hall of Fame ballot for 2023. He is in the non-competitive category which is pretty stacked with the likes of Travis Pastrana, etc. They’re taking two. If you remember Rick and what he did for motorcycling in the U.S., lend your voice to the movement. Here’s the link: https://americanmotorcyclist.com/hall-of-fame-class-of-2023


We are currently testing the 2023 Beta 300RR Race Edition. This is a premium version of the classic 300cc two-stroke off-road bike. It does not have oil injection, but it has a long list of upgrades, including KYB suspension at both ends. The motor is also in a more aggressive state of tune, between a larger exhaust port, different power valve timing and a higher compression head. Under it all is a traditional design with a Keihin carburetor and a mechanical power valve. Check out our test of the bike on the trails around Glen Helen Raceway with Sean Lipanovich behind the bars. More on the Beta next week!



See you next week!

–Ron Lawson

Comments are closed.