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

O.S. ENGINES NEEDLE RATCHET SPRING NO.4
Price:
AUD$7.64
Brand:
O.S. Engine
Model:
OS26711305
GTIN:
4531028114241
Condition:
Brand New
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No.4 Needle Ratchet Spring - Function and Tips

The No.4 needle ratchet spring is intended for use in O.S. Engine carburettor needle assemblies, providing the tactile detent that lets the needle hold discrete tuning positions. That predictable click pattern makes step-by-step tuning simpler.

Functionally the spring aids reliable idle settings and smoother throttle response by ensuring consistent ratchet feel under vibration and throttle loads. Replace the spring if the indexing becomes vague or clicks stop registering cleanly.

Install the spring with care using fine pliers and avoid squashing the coil; verify the needle moves freely and carry out a short run to confirm correct behaviour before full operation.

How should I use the ratchet clicks when tuning needle position?

Use the clicks as consistent increments: adjust by a known number of clicks when changing mixture or idle to reproduce prior settings reliably during tuning sessions.

Will a weak spring affect throttle response?

Yes, reduced detent force can let the needle shift under vibration, causing inconsistent mixture at partial throttle and less predictable throttle transitions.

Any bench checks recommended after fitting?

After fitting, cycle the throttle and count clicks to confirm clear indexing, then run the engine briefly at idle and part throttle to verify stable behaviour before full testing.

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