| Specification | Value |
|---|---|
| Model Code | CE16C/1SRJ |
| Year | 2015 |
| Engine Oil | Yamalube 4 (10W-30) / SAE 10W-30 (JASO MA) |
| Oil Capacity | 0.70 Liters |
| Spark Plug | NGK BR9EG |
| Front Tire | 80/100-21 51M |
| Rear Tire | 100/90-19 57M |
| Tire Pressure | 1.0 bar (15 psi) F/R |
Engineering Highlight: The SSS Legacy
The 2015 Yamaha YZ 125 (CE16C/1SRJ) represents a pivotal moment in the evolution of the world’s most popular two-stroke motocrosser. While the engine architecture remained largely unchanged from previous iterations, the 2015 model introduced the modern plastics and ergonomic profile found on the four-stroke YZ-F line. Most importantly, it continued the utilization of the KYB Speed Sensitive System (SSS) front forks—widely considered the benchmark for production suspension, utilizing a mechanical piston to control damping based on fork speed rather than position.
Performance Analysis
The CE16C/1SRJ is powered by a liquid-cooled, 124cc reed-valve inducted two-stroke engine. The power delivery is characterized by its explosive mid-range and impressive over-rev capabilities. For professional riders, the 2015 chassis refinement offered a more aggressive stance, allowing for tighter cornering and improved rider mobility across the seat. Weighing in at approximately 94kg (wet), its power-to-weight ratio remains competitive even against modern EFI competitors.
Maintenance Guide & Technical Specs
Lubrication System
The transmission requires 0.70 liters of high-quality oil. MotoSpecsLab recommends Yamalube 4 (10W-30) or any SAE 10W-30 oil meeting the JASO MA standard to ensure proper clutch engagement and gear protection. Frequent oil changes are vital due to the high-revving nature of the 125cc powerplant.
Ignition and Combustion
The 2015 YZ 125 utilizes the NGK BR9EG spark plug. This fine-wire electrode plug is designed to resist fouling while providing a consistent spark under high-compression racing conditions. Always check the gap and color of the plug to monitor the engine’s jetting health.
Chassis and Contact Patch
To maintain the bike’s legendary handling, tire pressure should be strictly monitored. The factory recommends 1.0 bar (15 psi) for both the front (80/100-21) and rear (100/90-19) tires. Lower pressures may be used for increased traction in soft sand, but risk rim damage in hard-pack conditions.
MotoSpecsLab Editorial Verdict
The 2015 YZ 125 remains a masterclass in mechanical simplicity and pure riding enjoyment. Its ease of maintenance, combined with the reliability of the CE16C platform, makes it an ideal choice for both aspiring racers and seasoned veterans who appreciate the tactile feedback of a well-tuned two-stroke.