UCAL UCD29-16 Carburettor Assembly – Royal Enfield Thunderbird 350 BS4 (OE Ref 576583/C) – Genuine UCAL BS4 UCE 350 Carb

Bring your BS4 Thunderbird 350 back to its original smoothness with the genuine UCAL UCD29-16 carburettor assembly (OE ref 576583/C). This is the BS4-spec 29 mm UCAL carb used by Royal Enfield’s OEM supply chain for the Thunderbird 350 UCE BS4 platform, calibrated specifically to meet BS4 emissions while keeping the classic RE thump and strong low-end torque. UCAL’s own catalogue and MRP list map UCD29-16 directly to “Royal Enfield Thunderbird 350cc – BS IV, OE 576583/C”, confirming exact application.

If your bike is hard to start, idling unevenly, or leaking from a worn-out carb, a fresh OEM-grade assembly is the cleanest fix. UCD29-16 restores crisp throttle response, stable idle and predictable fuel economy, without trial-and-error jetting or local duplicate issues.

Under The Hood sources UCAL carburettors only through verified distributors, packs them securely, and ships with GST invoice and expert support. If you’re unsure between BS3/BS4 or E20 upgrade options, you can also cross-check our dedicated BS29 E20 carb listings (RLT00240/A, RLT00241/A) and reach out for guidance before ordering. This listing is positioned mainly for riders who want a direct BS4-era UCAL replacement on their Thunderbird 350 without changing to a newer E20 carb kit.

Key Features

• Genuine UCAL carburettor – model UCD29-16, OEM vendor to Royal Enfield for BS4 Thunderbird 350.

• Correct BS4 calibration for 346 cc UCE engine – restores factory-like starting, idle and mid-range.

• OE reference 576583/C – matches UCAL catalogue mapping for Thunderbird 350 BS IV applications.

• 29 mm venturi (UCD29 family) designed to maintain proper air-fuel ratio across city, highway and touring use.

• Built from high-grade aluminium body with precision-machined passages for consistent atomisation and long service life.

• Direct-fit replacement on OE manifold and airbox for Thunderbird 350 BS4 carb versions – no fabrication required.

• Ideal fix for hard starting, fuel leakage, poor pickup or tuning nightmares caused by worn or duplicate carbs.

• Sourced, quality-checked and packed by Under The Hood, Varanasi – genuine-only policy and safe pan-India shipping.

Compatibility Table

Important Fitment Note:

• For Thunderbird 350 BS4/ABS, UCD29-16 is factory-mapped and safe as a direct replacement.

• For Classic/Standard/Electra 350 BS4, we recommend using Royal Enfield RLT00240/A E20 carb where possible. Only choose UCD29-16 if you are matching an existing UCAL carb with the same number on the body, or after confirming via parts portal / your mechanic.

Variants

This UCAL listing covers a single variant:

• UCD29-16 – BS4-spec carburettor for RE UCE 350 (Thunderbird focus), OE ref 576583/C.

If you want an E10/E20 dual-fuel upgrade instead of original BS4 spec, please see:

• RLT00240/A – BS29 E20 carb for BS4 Classic / Standard / Electra (Under The Hood listing – internal link).

What’s in the Box

• 1 × UCAL UCD29-16 carburettor assembly (pre-assembled body with slide, float bowl, jets as supplied by UCAL)

• Factory packaging / label with UCD29-16 and OE cross-reference (576583/C)

• Under The Hood invoice & packing slip

(Ancillaries like manifold rubber, clamps, throttle/choke cables and air-filter are not included – available separately on underthehood.co.in.)

Installation & Maintenance Notes

• Always install with a fresh manifold adaptor & O-ring for BS4 UCE (e.g., RE adaptor 576618/B) to avoid air leaks.

• Sync the idle speed and air-screw per Thunderbird 350 BS4 workshop guidelines after installation.

• Use a clean in-line fuel filter and ensure your tank is free from rust or debris before starting the new carb.

• Recommended cleaning interval: inspect and clean jets every 10,000–12,000 km in dusty or ethanol-heavy fuel conditions.

• For E20-dominant fuel areas, consider switching to E20-ready carb/E20 kit rather than repeatedly re-tuning a BS4-era carb.

FAQs

Q1. Will UCAL UCD29-16 fit my Thunderbird 350 BS4 / ABS?
Yes. UCAL’s own catalogue and MRP sheet map UCD29-16 (OE 576583/C) directly to Royal Enfield Thunderbird 350cc – BS IV, making it a confirmed fit for TB350 BS4/ABS carb models. Always match your existing carb / parts manual to be sure.

Q2. Can I use this on a Classic / Standard / Electra 350 BS4?
Physically it’s the same 29 mm UCAL BS4 carb family that some sellers list for BS4 UCE 350s, but catalogues conflict: UCAL maps UCD29-16 specifically to Thunderbird 350 BS4, while Royal Enfield’s E20 documentation chains 576583/C mainly through Classic/Std/Electra. We therefore mark these models as ❓ and recommend using RLT00240/A E20 BS4 carb unless you confirm via parts portal or by reading your current carb’s part code.

Q3. Is this original UCAL or a local duplicate?
Under The Hood only lists genuine UCAL product, sourced via authorised distributors with UCAL box labels, MRPs and correct UCD29-16 coding. No loose, unbranded or “open” carbs are sold as new.

Q4. Will this improve performance over my old carb?
Compared to a worn / leaking carb, a fresh UCD29-16 typically restores clean throttle response, smoother idle, fewer flat-spots and more consistent fuel economy, bringing the bike back to stock BS4 behaviour. It’s not a racing upgrade, but it removes tuning problems caused by clogged jets or warped bodies.

Q5. Is it E20 compatible?
UCD29-16 is a BS4-era carb tuned for standard petrol/E10. If your area has high E20 penetration, we recommend moving to RE’s E20 upgrade carb/kit (like RLT00240/A / RLT00241/A) instead of relying on this BS4-only calibration long-term.