Idle screw, PHVA/PHVB

Idle screw for PHVA / PHVB carburettors – a precision adjusting screw for Dell’Orto PHVA and PHVB carburettors. This part lets you set the engine's idle speed (idle RPM) by adjusting the position of the throttle slide at idle.

It is one of the most important carburettor adjustment parts, ensuring the engine runs steadily with the throttle closed.

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Purpose

• adjusting the idle speed
• stabilising the engine at idle
• correcting an idle that is too low or too high
• fine-tuning the carburettor

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Advantages

• precise, sensitive adjustment
• steady engine running at idle
• fits OEM and performance PHVA/PHVB carburettors
• simple fitting with no modifications
• durable metal construction
• resistant to vibration and fuel

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Compatibility

• Dell’Orto PHVA carburettors
• Dell’Orto PHVB carburettors
• Piaggio 2T scooters
• Minarelli Horizontal / Vertical (with PHVA/PHVB)
• Aprilia, Yamaha, MBK, Gilera models with these carburettors

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When should it be replaced?

Replacement is recommended when:

• the screw is worn or "no longer adjusts"
• the idle is unstable
• the screw is broken or stuck
• the idle is difficult to set

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Important

After adjustment, you must:

• also adjust the air/fuel mixture
• make sure the engine runs steadily when warm
• check the slide opening and the throttle cable