Vortex 641AZK-51 Aluminum Rear Sprocket 51-Tooth Black Anodized

The Vortex 641AZK-51 is a 51-tooth aluminum rear sprocket with a black anodized finish, designed for high-performance motorcycle applications. Manufactured in the USA, this sprocket is CNC-machined from a specially formulated aluminum alloy per Vortex specifications, delivering an ideal balance of lightweight performance and durability.

The black anodized surface treatment provides corrosion resistance while giving the sprocket an aggressive, race-ready appearance. Strategically placed lightening holes throughout the sprocket body reduce rotating mass, contributing to improved throttle response and acceleration feel. The unique Vortex tooth profile is engineered to extend sprocket service life and ensure smooth, consistent chain engagement.

Key Features:

• 51 teeth for optimized final drive gearing
• Lightweight aluminum construction — reduces rotating mass versus OEM steel sprockets
• Black anodized finish for corrosion resistance and visual appeal
• 100% CNC manufactured in the USA to precise tolerances
• Specially formulated aluminum alloy per Vortex specifications
• Lightening holes throughout for maximum weight reduction
• Unique tooth geometry engineered for extended wear and smooth chain engagement

Vortex Racing has been producing top-quality motorcycle drivetrain components for road racing, motocross, supercross, and flat track applications for over 15 years. Each sprocket is developed with direct feedback from professional race teams, making the 641AZK-51 a trusted upgrade for both track and street use.