O.S. Engine OS26711305 Carburettor Needle Ratchet Spring No.4  [OS26711305]

Spring No.4: Carburettor Needle Ratchet Function

This replacement ratchet spring fits inside O.S. Engine carburettor needle assemblies and supplies the small return and detent force required for accurate needle indexing. It keeps the needle registering distinct clicks so tuning steps remain repeatable.

In day-to-day use the spring supports stable idle and cleaner throttle transitions by maintaining dependable ratchet tension. Inspect for signs of wear or corrosion and replace the spring if the ratchet feels weak or the clicks are inconsistent.

When fitting, handle the spring carefully with fine pliers to avoid deforming the coil and confirm the needle slides freely after assembly. Run a short bench test and adjust gently to prevent overtightening the carburettor components.