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

Spring Specification and Fit

The O.S. Engine OS45582521 spring is supplied as an FSa-110 70N replacement for regulator assemblies on RC engines. It establishes a 70N preload that the regulator linkage must overcome to alter throttle position and control engine speed.

Mechanically the spring provides a static counterforce to the regulator arm; that counterforce sets the starting tension the governor works against, so altering spring rating changes the regulator's sensitivity and response time under load.

Fitting advice: install the OS45582521 into the designated FSa-110 spring cup so it seats centrally and the spring axis aligns with the regulator arm and linkage. After refit, perform stepwise bench trials or secure the model and observe idle and governor engagement before running freely. Check that pins and catches move without obstruction.

Tuning notes: this 70N unit is useful when you want a firmer baseline tension. If you notice a raised idle or delayed governor engagement after fitting, inspect seating and linkage geometry first, then consider a different spring rating only after measured testing.