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

Regulator Spring for FSa-110

This O.S. Engine regulator spring is an RC-scale replacement part listed as OS45582521 and labelled FSa-110 70N. It serves the regulator or governor assembly on compatible FSa-110 regulator housings, providing a defined 70N preload that sets the basic tension the regulator must overcome during engine speed control.

In practice the spring's role is purely mechanical: it sets the counterforce against the regulator linkage so that the engine maintains a target speed under varying load. Swapping to this 70N unit changes the regulator's baseline resistance compared with lighter or heavier springs, affecting how quickly the regulator reacts when throttle or load changes occur.

Installation notes: this is a direct-fit spring for the regulator assembly position indicated by the FSa-110 designation, it must seat cleanly in the spring cup and align with the regulator arm and linkage. After replacement, perform progressive tests on the bench or with the model restrained, verifying idle stability and governor response before full operation. Keep the part and surrounding regulator components free of debris and ensure linkage pins and catches move smoothly to avoid binding.

Tuning guidance: use this 70N spring when you want a mid-to-firm baseline tension in the regulator. If the engine shows high idle or slow governor engagement after fitment, recheck seating and linkage geometry before changing to a different spring rating. Changes are best evaluated incrementally so you can observe effects on idle, throttle snap, and steady-state rpm control.