Sunstar Rear Sprocket 40T Yamaha YZ400F 1998 5-367940

A quality rear sprocket is fundamental to your YZ400F's acceleration, top-end speed, and overall drivetrain efficiency. The SUNSTAR 40T delivers measurable performance gains through precision engineering and aerospace-grade materials that reduce unsprung weight while maintaining the rigidity required for aggressive riding. Whether you're maximizing trail performance or replacing worn sprocket teeth, this purpose-built component ensures consistent power delivery and extended service intervals.

Engineered from 7075 T-6 aluminum, this sprocket combines the strength of steel with a significant weight reduction—critical for maintaining snap throttle response and reducing rotational inertia. The exclusive tooth-valley design increases chain contact area by 50%, translating to smoother power transfer and reduced chain wear. Hard anodized finishing resists corrosion and abrasion, while strategically placed weight reduction holes and cleaning grooves extend maintenance intervals without compromising structural integrity.

• 40-tooth rear sprocket
• Yamaha YZ400F specific
• 7075 T-6 aluminum construction
• Weight reduction holes
• 50% increased chain contact
• Hard anodized finish
• Cleaning grooves included
• Bolt-on installation
• MPN: 5-367940