S&S CYCLE Breather Reed Valves for Evolution Big Twin 1993-1999, +0.030" Oversize – Part Number 31-2100

Breather Reed Valves - Crankcase - +0.030" Oversize - Evolution Big Twin '93-'99

Enhance your Harley-Davidson Evolution Big Twin engine with the S&S CYCLE Breather Reed Valves (Part Number 31-2100). Designed for models from 1993 to 1999, these valves feature a modern design that eliminates reliance on crankshaft rotation to operate. Instead, the reeds open when crankcase pressure exceeds cam chest pressure and close when the pressures equalize, providing on-demand operation for improved engine efficiency. This automatic adjustment helps compensate for lag in airflow during acceleration, resulting in increased performance and reduced high-rpm oil carryover, especially in engines with marginal piston ring sealing.
Installation is straightforward with no need for aligning timing marks or rotating parts, making it a convenient upgrade for mechanics and enthusiasts alike. Made in the USA, these reed valves are crafted with precision to ensure durability and optimal function in demanding riding conditions. The oversize +0.030-inch version ensures a precise fit and enhanced airflow management, contributing to smoother engine operation and longevity.
Whether you're restoring a vintage Harley or boosting the performance of your existing engine, the S&S CYCLE breather reed valves provide a reliable, high-quality solution. Designed to meet the rigorous demands of big twin engines, they help maintain proper crankcase ventilation, reduce oil contamination, and support overall engine health. Trust S&S CYCLE’s commitment to craftsmanship and performance with this essential upgrade for your Harley-Davidson Evolution engine.

Features:

• Advanced on-demand reed operation that opens when crankcase pressure is higher than cam chest pressure

• Designed specifically for Harley-Davidson Evolution Big Twin engines from 1993 to 1999

• Oversize +0.030-inch for enhanced airflow and performance

• Easy installation without the need for timing mark alignment or rotating parts

• Made in the USA with high-quality materials for durability and reliability