Rear Sprocket 40T 6.43 BC 520 Chain

The Rear Sprocket 40T 6.43 BC 520 Chain from M and W Aluminum Products is a precision-engineered sprocket designed for high-performance motorcycle, ATV, and powersports applications where chain drive reliability is essential. This 40-tooth sprocket is ideal for riders and operators who demand consistent power transfer and extended component lifespan, making it suitable for both street and off-road environments.

Machined from lightweight aluminum alloy, the 40T sprocket features a 6.43-inch bolt circle diameter (BC) for precise fitment to 520-series chain systems, which are the industry standard for mid-range power applications. The 520 chain pitch (5/8-inch spacing) is engineered for optimal load distribution and engagement geometry, reducing side-loading and premature wear on both sprocket teeth and chain rollers. This aluminum construction minimizes unsprung weight, improving acceleration response and reducing drivetrain inertia.

This sprocket is perfect for operators who require dependable drivetrain performance in various applications. The precision tooth profiling ensures smooth power delivery across the entire RPM band, while the measured 6.43 BC specification guarantees compatibility with OEM and aftermarket hub assemblies. Whether replacing a worn sprocket or upgrading your drivetrain, this product provides the durability and performance foundation needed for reliable operation.