971184 Lockwasher, crankpin nut

When you're working inside the bottom end of a vintage 45" sidevalve, small details like the crankpin nut lockwasher make all the difference. This MCS lockwasher is a critical component for securing the crankpin nut and preventing it from backing off under the stresses of engine operation. It fits 1916 to 1973 45" SV models and is a direct replacement for OEM 23982-12 and 971184. Typically, two of these are used per assembly to ensure the rotating mass stays locked tight. Having a few extras on the bench is always a good idea when rebuilding these classic engines, as they are essential for a safe and successful bottom-end overhaul.