## Key Features
✅ Premium Material & CNC Craftsmanship
High-strength carbon structural steel with forging process. Sprocket teeth go through high-frequency quenching. CNC milled tooth profiles follow original chain track geometry for smooth meshing, reducing chain jumping and abnormal noise. Black-oxide anti-rust surface treatment defends against rain and mud corrosion, extending service life for both sprocket and drive-chain assembly.
✅ Perfect Fitment & Custom Tooth Options
Compatible with 428 drive chain. Mounting hole pattern fully matches Yamaha K1 (YBR125-K1) stock rear hub, direct bolt-on installation with zero modification to wheel hub or cushion rubber.
Stock standard tooth: 43T. Custom tooth counts available: 41T /42T /44T /45T. Larger teeth boost low-end torque for city traffic; smaller teeth improve top-speed performance for highway cruising.
✅ Optimized Transmission Performance
Accurate tooth clearance minimizes power loss and running noise. Stress-optimized mounting holes lower risks of tooth fracture or deformation under heavy-load riding. Adjust gear ratio freely to upgrade acceleration or highway performance.
✅ Simple Installation & Maintenance Friendly
Direct swap for original worn parts. Work with stock cushion rubber to absorb engine impact and cut rear wheel vibration. Highly recommended to replace sprocket together with front sprocket and chain as one complete set. Regular chain lubrication will further prolong component lifespan.
## Application Scenarios
- OEM replacement: Replace worn, hooked-tooth or jump-causing factory sprockets
- Gear-ratio tuning: Adjust torque & top-speed for city commuting & mountain road riding
- Bulk supply for repair shops & aftermarket distributors
Specifications
Item | Parameter |
|---|
Fitment | Yamaha YBR125‑K1 (Yamaha K1) |
Chain Type | 428 |
Standard Tooth | 43T (Custom:41/42/44/45T) |
Material | Carbon steel, teeth high‑frequency quenched |
Surface Finish | Black oxide anti‑rust treatment |
Mounting | Bolt‑on to original rear flange, no modification needed |
## Notes
1. Replace immediately if sprocket shows cracked, hooked or heavily-worn teeth, to avoid sudden-chain-break safety hazards.
2. Inspect chain wear condition during replacement; full kit replacement is preferred.
3. Avoid extreme tooth-count adjustment, which may accelerate extra wear on clutch and chain system.
## Factory Custom Service
As a professional CNC machining manufacturer, we accept custom motorcycle rear sprocket orders for diverse motorcycle models. Send your drawing or sample for quotation.
