O.S. Engine OS45582521 Regulator Spring FSa-110 70N  [OS45582521]

FSa-110 Spring Overview

This O.S. Engine part OS45582521 is a precision replacement regulator spring marked FSa-110 70N for RC engine regulator assemblies. It provides a fixed 70N preload that defines the counterforce on the regulator linkage, helping control engine speed under varying load.

The spring functions purely mechanically: it resists regulator movement so the governor holds or releases throttle as required. Moving to this 70N unit alters the baseline resistance relative to lighter or heavier springs and changes how the regulator responds to throttle and load transitions.

Installation notes: the OS45582521 fits the regulator position identified by FSa-110 and must be seated squarely in the spring cup so it aligns with the regulator arm and linkage. After fitting, run incremental bench checks or restrain the model for a controlled start up, confirming idle stability and governor reaction before full use. Keep the area clean and verify linkage pivots are free to move to prevent binding.

Tuning guidance: choose this 70N spring when you need a mid to firm baseline tension in the regulator. If you encounter high idle or sluggish governor engagement, first recheck seating and linkage geometry before trying a different spring rating. Make small adjustments and observe changes to idle, throttle snap, and steady rpm to evaluate effects.