Replacement Needle Set for RC Carburettors OS27981910 by O.S. Engine  [OS27981910]

Needle codes and replacement use

This product lists the O.S. Engine OS27981910 needle codes 20M, 40E, 60B, 60G, 60H and 60L intended as replacement needles for carburettor needle valves on RC glow engines. Each code denotes the needle profile used to match the original fuel characteristics during service or overhaul.

To fit, remove the carburettor top, withdraw the old needle assembly, inspect the seat and needle tip for scoring or debris, and replace with the matching code. Reassemble carefully and confirm there are no fuel leaks before testing the engine.

Carry out stepwise tuning after a swap: bench checks followed by a short test run. Needle profile affects idle, midrange and full throttle response; use cautious adjustments, watch engine temperature, and refine mixture and idle screw positions until running is smooth.