| Specification | Value |
|---|---|
| Model Code | CG23C / 1SSN |
| Production Years | 2015–2016 |
| Engine Oil | Yamalube 4 (10W-40) / JASO MA (0.75 L) |
| Spark Plug | NGK BR8EG |
| Tire Size (Front/Rear) | 80/100-21 / 110/90-19 |
| Tire Pressure | 1.0 bar (15 psi) |
Engineering Heritage: The Resilience of the YZ Platform
The Yamaha YZ 250 holds a unique distinction in the motocross world: it is the only Japanese 250cc two-stroke to remain in continuous production since the early 1970s. The 2015-2016 (CG23C/1SSN) generation represents a pivotal moment in the model’s history, where Yamaha modernized the aesthetics with updated ‘arrow’ styling and introduced the industry-leading KYB Speed Sensitive System (SSS) fork internals to the aluminum chassis first pioneered in 2005. This combination of a proven power plant and elite suspension makes it a benchmark for reliability and handling.
Technical Engine Analysis
The heart of the CG23C is the 249cc liquid-cooled, reed-valve inducted two-stroke engine. Known for its broad powerband, the YPVS (Yamaha Power Valve System) provides a torque curve that many modern four-strokes struggle to emulate in terms of immediate delivery. For peak performance, the engine requires a precise 0.75 L transmission oil change using Yamalube 4 (10W-40). Maintaining the JASO MA standard is critical to prevent clutch slippage under high-load racing conditions.
Chassis and Suspension Maintenance
The 2015-2016 models utilize an advanced semi-double-cradle aluminum frame. Maintenance focus should remain on the linkage bearings and the KYB SSS front forks. Unlike air-fork competitors of the same era, the YZ 250’s spring-based system offers consistent damping throughout a moto. Tire pressure is standardized at 1.0 bar (15 psi) for both the 80/100-21 front and 110/90-19 rear, providing the necessary footprint for varied terrain.
Maintenance Schedule Quick-Reference
- Spark Plug: Inspect and gap the NGK BR8EG every 5 hours; replace as needed to prevent fouling.
- Transmission Oil: Change every 5-10 hours of operation depending on riding intensity.
- Air Filter: Clean and re-oil after every ride to protect the cylinder from debris.
- Chain Tension: Check and lubricate regularly, maintaining 48-58mm of slack.
Conclusion
The Yamaha YZ 250 (CG23C/1SSN) remains a favorite among purists and competitive racers alike. Its mechanical simplicity, combined with high-tier suspension components, ensures that with proper adherence to the technical specifications outlined above, the machine provides a professional-grade racing experience with significantly lower maintenance overhead than its four-stroke counterparts.