YAMAHA YZ125 2018 — Full Specifications, Performance, and Market Comparison

The YAMAHA YZ125 2018 is a lightweight, competition-focused two-stroke motocross motorcycle designed for riders who prioritize agility, acceleration, and race-ready handling. As one of the few modern 125cc two-stroke models still in active production, the YAMAHA YZ125 2018 remains a benchmark in the 125cc motocross class, known for reliability, simplicity, and strong aftermarket support.

Engine and Performance Overview

The YAMAHA YZ125 2018 features a 124–125cc liquid-cooled, single-cylinder, two-stroke engine with reed-valve induction and Yamaha Power Valve System (YPVS).
It uses a Mikuni TMX 38 mm carburetor and a premix lubrication system, delivering sharp throttle response and high-revving performance.

Key engine specs:

Displacement: 125cc
Bore × Stroke: 54.0 mm × 54.5 mm
Compression Ratio: 8.6:1 – 10.7:1
Cooling System: Liquid-cooled
Ignition: CDI
Starter: Kick start
Transmission: 6-speed constant mesh
Final Drive: Chain

The YAMAHA YZ125 2018 is tuned for strong mid-range pull and aggressive top-end power, making it ideal for competitive motocross and advanced off-road riding. Total Motorcycle

Chassis, Suspension, and Handling

The YAMAHA YZ125 2018 uses a lightweight aluminum semi-double cradle frame designed to maximize rigidity while keeping overall weight extremely low.

Suspension system:

Front Fork: KYB Speed-Sensitive System inverted fork, 300 mm travel
Rear Shock: KYB single shock with linkage, 315 mm travel

Brakes and Tires:

Front Brake: Hydraulic disc (250–270 mm depending on market)
Rear Brake: Hydraulic disc (245 mm)
Front Tire: 80/100-21
Rear Tire: 100/90-19
Stock Tires: Dunlop MX52

This suspension setup gives the YAMAHA YZ125 2018 excellent cornering stability, jump absorption, and precise track feedback.

Dimensions, Weight, and Ergonomics

The YAMAHA YZ125 2018 is engineered to feel light, responsive, and race-oriented.

Key dimensions:

Wet Weight: ~94 kg (207 lb)
Seat Height: 975 mm (38.4 in)
Wheelbase: 1445 mm
Ground Clearance: ~363–366 mm
Fuel Tank Capacity: 8.0 L (2.1 gal)

Its lightweight build gives the YAMAHA YZ125 2018 a competitive power-to-weight advantage, allowing quick direction changes and easy maneuverability on technical tracks.

Reliability, Maintenance, and Ownership Costs

One of the strongest advantages of the YAMAHA YZ125 2018 is mechanical simplicity.
Compared to four-stroke motocross bikes, two-stroke engines generally offer:

Lower rebuild costs
Fewer moving parts
Faster top-end servicing
Strong aftermarket parts availability

Routine maintenance mainly involves air filter servicing, premix fuel preparation, and periodic piston/ring inspections.

Comparison With Related 125cc Competitors

YAMAHA YZ125 2018 vs KTM 125 SX

KTM offers fuel injection in newer generations
Yamaha is known for smoother power delivery and lower maintenance cost

YAMAHA YZ125 2018 vs Suzuki RM125 (older models)

Yamaha benefits from modern parts availability
RM125 is discontinued, making long-term ownership harder

YAMAHA YZ125 2018 vs Kawasaki KX125

KX125 offers aggressive power delivery
Yamaha maintains a more balanced chassis feel and suspension refinement

Among its peers, the YAMAHA YZ125 2018 remains one of the most stable and race-ready platforms.

Pricing and Market Value

Original MSRP (market-dependent): Approx. $6,499 USD
Used market value (condition-dependent): $3,800 – $5,500 USD

The YAMAHA YZ125 2018 holds strong resale value due to demand, racing reputation, and Yamaha’s long-term parts support.

Ideal Rider Profile

The YAMAHA YZ125 is best suited for:

Motocross riders seeking a lightweight race bike
Riders upgrading from smaller displacement dirt bikes
Enthusiasts who prefer two-stroke simplicity and responsiveness

Its full-size frame accommodates a wide range of rider heights, making it competitive for teens and adults alike.

Final Verdict

The YAMAHA YZ125 continues to stand as one of the most respected 125cc motocross motorcycles ever produced. With lightweight construction, responsive power delivery, high-quality KYB suspension, and strong reliability, it remains a top choice for riders who value performance and precision in the 125cc class.