Five years after its debut, the Yamaha YZ125X two-stroke cross-country and enduro racer gets its first major update. While the 2022 Yamaha YZ125X is not entirely all-new, there are significant changes, including an all-new engine. It’s time to look more closely at this lightweight, high-performance woods bike.
- Although not every engine part is different this year, it’s changed enough to be considered a new powerplant. Starting from the new cylinder head and working down, the liquid-cooled two-stroke gets a new cylinder, piston, piston pin, connecting rod, and crankcase. The motor remains kickstart-only, and the 2023 Yamaha YZ125X still requires premix.
- The cylinder port timing and the shape of the ports are changed. Matching the new porting is revised power valve timing, plus a new expansion chamber with a shorter, lighter muffler.
- There’s a new Hitachi Astemo Keihin PWK38S carburetor feeding the case-induction motor. The Keihin replaces a Mikuni TMX 38 carb. We feel the disappointment of those who would have liked to have seen EFI replace carburetion. However, the PKW38S does have a throttle position sensor that works with mapping software in the CDI. Complementing the new carb is a straighter air intake housing a 4Force4 carbon reed valve.
- Yamaha claims increased power and improved throttle response across the rev range. A Yamaha insider tells us that the new motor has “clean, crisp throttle response, superior rideability and excellent over-rev character” with “improved usability and increased mid- and top-end power.”
- To retain reliability, the six-speed transmission is beefed up. The teeth in the gearbox are wider, and there are new ratios that reflect the power boost.
- The motor powerful motor inspired a new brake system. Although the front disc is still 270mm in diameter, the pad contact area is 30 percent larger than last year. The front caliper gets larger pistons and more rigidity. With the upgraded front brake performance, the rear disc’s diameter is reduced 5mm to 240mm to reduce unsprung weight. The rear sprocket is also lighter on the new X.
- The 2023 Yamaha YZ125X gets some minor suspension changes. The returning KYB suspension returns with revised shock settings and a new scraper in the fork legs to keep the fork tubes from bringing debris into the internals.
- Yamaha has upgraded the Dunlops on the YZ125X. The AT81s are replaced by a pair of MX33 tires. The front tire is 10mm narrower than last year, with the rear still a 110/90 on an 18-inch hoop.
- The YZ125-based frame is unchanged, and still optimized for cross-country racing.
- For easier rider movement, the seat is flatter than last year, and the radiator shrouds are narrower. The handlebar can be mounted in either of two positions.
- Yamaha narrowed the fuel tank this year, reducing its capacity by nearly 1.5 quarts to 1.8 gallons. This makes the 125 two pounds lighter with the tank filled.
- All the changes add three pounds to the wet weight of the 2023 Yamaha YZ125. It tips the scales at 212 pounds with the tank topped off with premix.
- The GNCC-aimed 2023 Yamaha YZ125X gets a $300 price boost. That includes new graphics for the Team Yamaha Blue plastic. It will arrive in dealers in September with an MSRP of $7099.
2023 Yamaha YZ125X Specs
- 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 Hitachi Astemo Keihin PWK carburetor
- Intake: Case-induction w/ VForce4 carbon reed valve
- Exhaust: Powervalve and expansion chamber
- Cooling: Liquid
- Starting: Kick
- Lubrication: Premix
- Transmission: Close-ratio 6-speed
- Clutch: Wet multiplate
- Chain: O-ring
- Frame: Twin-spar aluminum w/ aluminum square-tube subframe
- Handlebar: Aluminum
- Front suspension; travel: Fully adjustable KYB Speed-Sensitive System inverted fork; 11.8 inches
- Rear suspension; travel: Linkage-assisted, fully adjustable KYB piggyback shock; 12.4 inches
- Wheels: Excel
- Tires: Dunlop Geomax MX33
- Front tire: 80/100 x 21
- Rear tire: 110/100 x 18
- Front brake: 270mm disc
- Rear brake: 240mm disc
DIMENSIONS and CAPACITIES
- Wheelbase: 57.3 inches
- Rake: 26.4 degrees
- Trail: 4.4 inches
- Seat height: 38.2 inches
- Ground clearance: 14.0 inches
- Fuel capacity: 1.8 gallons
- Wet weight: 212 pounds
- Color: Team Yamaha Blue
2023 Yamaha YZ125X Price: $7099 MSRP
2023 Yamaha YZ125X Photo Gallery