21F Piston Pin Upgrade - O.S. Engine OS22406001  [OS22406001]

Service and fit piston pin

This O.S. Engine OS22406001 piston pin is presented as a straightforward replacement for RC engine rebuilds and scheduled maintenance. It is marked for use with 21F-series engines and functions as the bearing connection between piston and connecting rod.

Content concentrates on practical fitment and workshop checks rather than numeric specs. During assembly ensure the piston pin moves freely in the piston small end and seats correctly in the wrist pin bore prior to final assembly. Use appropriate workshop tools and careful technique to avoid scoring and misalignment.

Installation notes:

• Remove dirt and old residue from mating surfaces before fitting.
• Confirm a light sliding fit in the piston and small end; too much play or a tight fit indicates incompatibility.
• Adhere to the engine manufacturer's assembly order and torque recommendations for associated fasteners.