FS-series Rocker Arm Assembly for O.S. Engine OS45561010 (FS-120S / S-II / S-E / S-SP / FT-300)  [OS45561010]

FS-series valve rocker: role and compatibility

This rocker arm assembly is a replacement component specified by the manufacturer for use with the FS-series engines listed. It acts as the valve actuation linkage in the cylinder head and is used to correct geometry when wear or damage affects valve timing.

Fitment applies only to the model numbers shown in the product title; confirm the OS45561010 model number against your engine before purchasing. During engine service, always check clearances and ensure fastenings are secure when reassembling to preserve predictable engine response at model power levels.

In tuning and maintenance the rocker arm affects valve timing and transient response, so verify rocker alignment and rocker-to-valve clearance as part of any tune-up or replacement to maintain expected engine behaviour in RC applications.

Select this replacement when restoring valve linkage on the compatible FS engine models and perform standard reassembly checks for clearance and secure mounting.