Did you know? The Yamaha YBR 125 was engineered as a ‘Global Bike,’ designed to be manufactured in multiple continents (Brazil and China) while maintaining a standardized parts ecosystem. This strategic engineering choice made it one of the first 125cc motorcycles to successfully bridge the gap between high-volume utility and Japanese reliability standards, effectively replacing the aging SR125 with a modern SOHC architecture.
| Component | Specification |
|---|---|
| Production Years | 2005–2009 |
| Engine Oil | SAE 10W-40 JASO MA (1.0 L) |
| Front Tire / Pressure | 2.75-18 42P / 1.8 bar (25 psi) |
| Rear Tire / Pressure | 90/90-18 57P / 2.0 bar (29 psi) |
| Battery Type | RE05: YB5L-B | RE06: YTX5L-BS |
| Spark Plug | NGK CR6HSA |
Engineering Overview: The RE05/RE06 Evolution
The RE05 and RE06 designations represent the critical transition period of the YBR 125. These models feature a single-cylinder, air-cooled, 4-stroke SOHC engine. While the RE05 primarily utilized a carburetor system (Mikuni VM22), the RE06 variants began the shift toward stricter emission compliance. The engine is renowned for its internal balance shaft, which significantly reduces vibrations—a rarity in the budget 125cc class of that era.
Maintenance Protocol
1. Lubrication System
The YBR 125 utilizes a wet-sump lubrication system. For the RE05/RE06 series, 1.0 liter of SAE 10W-40 JASO MA oil is required. As these engines lack a traditional spin-on filter, it is vital to clean the internal oil strainer and the centrifugal filter during major services to prevent sludge buildup.
2. Drive Chain & Chassis
The 428-pitch chain requires regular adjustment. Maintain a slack of 20-30mm. Given the bike’s lightweight nature, tire pressure is critical for handling stability. Ensure the 2.75-18 front is at 1.8 bar and the 90/90-18 rear is at 2.0 bar (increase rear to 2.2 bar when carrying a passenger).
3. Ignition & Electrical
The RE05 uses a traditional lead-acid battery (YB5L-B) requiring periodic electrolyte checks, whereas the RE06 transitioned to the maintenance-free YTX5L-BS. Always check the NGK CR6HSA spark plug gap, which should be set between 0.6 and 0.7 mm for optimal combustion efficiency.
MotoSpecsLab Editorial Verdict
The RE05/RE06 generation of the YBR 125 remains the gold standard for mechanical simplicity. While it lacks the power of liquid-cooled competitors, its ease of maintenance and the availability of interchangeable parts make it a masterclass in pragmatic motorcycle engineering. For the DIY mechanic, there is no better platform to learn the fundamentals of motorcycle maintenance.