Product Description
The 570836/B Needle Assembly is an essential internal component of the UCAL/Mikuni BS29 Constant Velocity (CV) carburetor. This “Jet Needle 1.5” is responsible for metering the amount of fuel that enters the engine as the throttle slide rises.
Over thousands of kilometers, the needle can develop “steps” or visible wear marks on its tapered surface due to constant vibration against the needle jet. This wear often leads to common performance issues like mid-range flat spots, engine surging, poor throttle response, or increased fuel consumption. Replacing your worn needle with this genuine OEM assembly restores the factory-calibrated fuel taper, ensuring your 350cc UCE engine runs crisply and efficiently throughout the RPM range.
Key Features:
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Authentic OEM Part: 100% Genuine Royal Enfield spare (PN: 570836/B) for precise fueling and tuning stability.
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Restores Mid-Range Power: Corrects fuel delivery issues between 1/4 and 3/4 throttle openings.
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Factory Calibration: Features the specific “1.5” taper profile required for the 350cc Unit Construction Engine (UCE).
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High-Precision Machining: Made from durable, wear-resistant alloy to ensure longevity under high-frequency movement.
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Direct Fitment: A “drop-in” replacement for the standard BS29 CV carburetor slide assembly.
Technical Specifications:
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Part Number: 570836/B
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Type: Jet Needle Assembly (Needle Assy 1.5)
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Compatible Carburetor: BS29 CV Carburetor
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Material: Precision Grade Brass/Alloy
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Quantity: 1 Number
Vehicle Compatibility:
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Royal Enfield Classic 350 (Carbureted BS3 & BS4 Models)
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Royal Enfield Bullet 350 & Bullet ES (UCE Models)
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Royal Enfield Thunderbird 350 / TBTS / 350X
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Royal Enfield Electra 350 UCE
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Royal Enfield Machismo A350 & A500
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Note: Not compatible with BS6 (EFI) models or the new J-Series Classic Reborn/Meteor.










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