| Specification | Technical Data |
|---|---|
| Model Code | RE40-R125/25 |
| Production Years | 2019–2022 |
| Engine Oil | SAE 10W-40 (API SG+, JASO MA) – 1.00 L |
| Front Tire | 100/80-17 M/C 52H (1.75 bar / 25 psi) |
| Rear Tire | 140/70-17 M/C 66H (2.00 bar / 29 psi) |
| Spark Plug | NGK CPR8EA-9 (Gap: 0.8–0.9 mm) |
| Battery | YTZ6V |
The 2019–2022 Yamaha YZF-R125 (RE40) represents a significant engineering milestone: it was the first 125cc supersport to integrate Variable Valve Actuation (VVA). This system uses a solenoid-activated cam profile switch at 7,400 RPM, allowing the engine to maintain high-end power without sacrificing low-end torque—a feat previously reserved for high-capacity machines.
Technical Review: The RE40 Evolution
From a mechanical perspective, the RE40 generation moved the R125 from a simple commuter-based engine to a sophisticated performance unit. The inclusion of a Slipper & Assist clutch reduced lever effort and stabilized the chassis during aggressive downshifts. The Deltabox frame geometry was refined to accommodate a wider 140-section rear tire, improving mechanical grip and footprint consistency during lean.
Maintenance Guide
Lubrication System
The RE40 engine is highly sensitive to oil shear due to its high-revving nature (VVA engagement). We recommend a high-quality synthetic SAE 10W-40. The total capacity is exactly 1.00 liter. Ensure the oil meets JASO MA standards to prevent clutch slippage.
Ignition & Electrical
The NGK CPR8EA-9 spark plug is critical for the VVA system’s timing accuracy. The gap must be precisely set between 0.8 and 0.9 mm. For the electrical system, the YTZ6V battery provides the necessary cold-cranking amps for the high-compression start cycles.
Chassis & Tires
The RE40 utilizes a 100/80-17 front and a 140/70-17 rear. Maintaining the factory pressure of 1.75 bar (Front) and 2.00 bar (Rear) is vital for the agility of the bike. Under-inflation leads to heavy steering and premature wear on the side walls.
Editorial Verdict
The Yamaha YZF-R125 RE40 remains the benchmark for the A1 license category. Its build quality mimics the R6 and R1, offering a ‘big bike’ feel with surgical precision. For owners, strict adherence to the 1.0L oil capacity and VVA-specific spark plug gap is the key to longevity.
Frequently Asked Questions
How often should I check the spark plug?
We recommend inspecting the NGK CPR8EA-9 every 6,000 km, especially if the bike is frequently ridden in the VVA power band.
Can I use 10W-30 oil?
While some regions allow it, MotoSpecsLab recommends 10W-40 to ensure adequate film strength at high operating temperatures.