517925 Lock kit, crank pin

This crank pin lock kit is a vital component for bottom-end rebuilds on 1954 to early 1981 Big Twin models. Sold as a complete kit, it provides the necessary hardware to secure the crank pin within the flywheel assembly, ensuring the rotating mass remains stable under load. It is a direct replacement for OEM 23971-54 and is manufactured to meet the rigorous demands of Shovelhead and early Evolution-era engines. When you are splitting the cases and refreshing the flywheels, using a fresh lock kit, also referenced as 517925, is cheap insurance against mechanical failure, keeping your Big Twin's heart beating reliably for years to come.