2020 Yamaha YZ125X First Look (17 Fast Facts)

June 7, 2019

2020 Yamaha YZ125X First Look: GNCC Racing Motorcycle

The resurgence of two-stroke off-road motorcycles continues with the 2020 Yamaha YZ125X. Based on the long-running Yamaha YZ125 motocrosser racer, the 2020 Yamaha YZ125X hits the GNCC and hare scrambles cross-country courses with a motor and chassis tuned to off-road racing.

Let’s take a look at what makes the 2020 Yamaha YZ125X suited to off-road racing away from motocross circuits.

1. The 125cc motor has smoother power for the longer, technical GNCC courses. The little tiddlers can be screamers with narrow powerbands, but Yamaha didn’t go that route with the 2020 YZ125X. The YZ125X gets its own power delivery characteristics.

2. The YZ125X has its a unique power valve shape. The timing and duration of the power valve operation are optimized for off-road racing.

3. Yamaha gives the 2020 YZ125X a new cylinder head. The lower-compression head had a unique combustion chamber shape, to make the two-stroke more rideable.

4. The CDI gets digital settings to smooth out the power and widen the powerband.

5. A terrain-resistant sealed O-ring chain sends the power to the rear sprocket.

6. For off-road racing, the YZ125X gets off-road wheels and tires. That means an 18-inch rear wheel, and Dunlop Geomax AT81 rubber. Both tires on the YZ125X are 10mm wider than the Dunlops on the YZ125.

7. We all like KYB’s fully adjustable speed-sensitive suspension, and the 2020 Yamaha YZ125X has it. As you’d expect, the YZ125X’s suspension settings are softer than the MX-friendly YZ125.

8. The wheelbase on the 2020 YZ125X is a half-inch longer than the YZ125. Going up to a 57.3-inch wheelbase increases stability for the higher speeds found in off-road racing.

9. The YZ125X’s rake is kicked out nearly a degree from the YZ125, and there is 0.3 inches more trail. Again, these are changes to make the YZ125X more stable at high speed. Given how light the YZ125 is, agility should still be impressive in tight quarters.

10. The seat height on the YZ125X is 0.8 inches lower than the YZ125. This will come in handy when the need arises to paddle through technical terrain.

11. A kickstand is standard on the YZ125X.

12. To let you know it’s time to get back to the truck, the 2020 Yamaha YZ125X’s petcock has a reserve position. Of course, we’ll prefer EFI, but Yamaha built the X to a price point. To be fair, the 38mm Mikuni TMX carburetor gives us little to complain about.

13. Important carry-over parts from the YZ125 include the aluminum frame, six-speed transmission, and 270mm front disc brake.

14. The wet weight of the 2010 Yamaha YZ125X is 209 pounds—up two pounds from the motocrosser. For comparison in Yamaha’s GNCC racer line, the YZ125X is 36 pounds lighter than the four-stroke YZ250FX and 20 pounds lighter than the two-stroke YZ250X.

15. Like the YZ250X, the YZ125X is kickstart-only. That simplifies things, as there is no need for a battery and the electrical system needed to support it. On the downside, you have to kick it to start it.

16. Oddly, ground clearance on the YZ125X is over a half-inch less than the YZ125. We prefer more ground clearance for rocky terrain, not less. Still, 13.8 inches of ground clearance isn’t bad.

17. The 2020 Yamaha YZ125X will hit the showroom floors this month with an MSRP of $6699. That is $100 more than the YZ125 MXer.

2020 Yamaha YZ125X Specs

ENGINE

Type: Two-stroke single
Displacement: 125cc
Bore x stroke: 54.0 x 54.5mm
Compression ratio: 7.4:1 to 8.8:1
Fueling: 38mm Mikuni TMX carburetor
Intake: Reed valve
Port timing: Power valve
Lubrication: Premix
Chain: O-ring

CHASSIS

Frame: Aluminum
Front suspension; travel: Fully adjustable KYB Speed-Sensitive System inverted fork; 11.8 inches
Rear suspension; travel: Linkage-assisted, fully adjustable KYB shock; 12.4 inches
Tires: Dunlop Geomax AT81
Front tire: 90/90 x 21
Rear tire: 110/90 x 18
Front brake: 270mm disc
Rear brake: 245mm disc

DIMENSIONS and CAPACITIES