Royal Enfield 500841 – O-Ring Float Chamber Cover (Ring CV Carburetor T1) for Classic 350, Bullet 350 UCE, Electra 350, Thunderbird 350

The Royal Enfield 500841 O-Ring Float Chamber Cover (T1) is the genuine float bowl gasket / ring for CV carburettors (CV28 / BS29 family) used on many 350cc and Machismo models. Official Royal Enfield part catalogues list 500841 as “O RING FLOAT CHAMBER COVER T1” in the CV carburettor section, grouped with the float assembly, float pin and main jets.

 Classic 350, Bullet 350 UCE (KS/ES), Electra 350 UCE (ES) and Thunderbird 350 (TBTS/NTB 350). Safexbikes and other suppliers map the same part to Machismo A350, Machismo A500 and early Thunderbird 350 (2002), all of which use the T1 CV carb system. eBay listings further describe it as a “Float Bowl Gasket CV28 500841” for Electra and Classic models.

A hardened, flattened or cut float bowl O-ring can cause fuel drips, petrol smell, poor idling and inconsistent tuning. Replacing it with the genuine 500841 restores a proper seal, making carburettor overhauls on Classic/Bullet/Thunderbird/Machismo engines reliable and leak-free.

Perfect for carb rebuilds, restoration projects, or preventive maintenance on UCE 350 and older Machismo/Thunderbird models, this is a direct-fit OEM ring—no local jugaad, no guessing.

Key Features 

• Genuine Royal Enfield part – Officially listed as “O RING FLOAT CHAMBER COVER T1 – 500841” in factory part lists.

• Purpose-built float bowl gasket – Seals the interface between CV carb body and float chamber cover on T1 CV carb assemblies.

• Verified multi-model fitment – Dealer listings confirm usage on Classic 350, Bullet 350 UCE KS/ES, Electra 350 UCE ES, Thunderbird 350 (TBTS/NTB), Machismo A350, Machismo A500, Thunderbird 350 (2002).

• Prevents fuel leaks & seepage – Fresh O-ring helps stop petrol drips from the carb bowl area and eliminates strong fuel odours.

• Stable carb tuning – A proper seal avoids false air/fuel disturbances, supporting consistent idling and mid-range performance.

• High-quality rubber compound – Designed to resist petrol and heat in long-term use, unlike cheap aftermarket rings that swell or crack early.

• Direct replacement – Exact size and profile for the OE float chamber cover; no trimming or sealant hacks required.

• Ideal for full carb overhaul kits – Pairs perfectly with 500843 float assembly, 500846 float pin and CV carb jets when rebuilding.

Compatibility Table 

Explicitly NOT listed / treat as incompatible:

• All J-Series models – Classic 350 J, Bullet 350 J, Meteor 350, Hunter 350 (EFI, no CV carb).

• 650 Twins – Interceptor 650, Continental GT 650, Super Meteor 650, Shotgun 650.

• Himalayan / Scram 411 and 450/Guerrilla 450 (different carb/EFI hardware).

• EFI 500s – Classic 500 / Bullet 500 / Thunderbird 500 EFI (UCD33 / EFI system).

Variants

• Single OEM variant:

  • Part Number: 500841

  • Description (OE): O-RING, FLOAT CHAMBER COVER T1 / Ring CV Carburetor

No LH/RH, colour or size variants.

FAQs 

Q1. What exactly is part 500841 used for?
A1. 500841 is the float chamber cover O-ring (ring CV carb). It sits between the float bowl and carburettor body on T1 CV carbs (CV28/BS29 family) and keeps the bowl sealed against fuel leaks and air leaks.

Q2. Which Royal Enfield models does 500841 fit?
A2. Dealer and catalog data confirm fitment on Classic 350 (carb UCE), Bullet 350 UCE (KS/ES), Electra 350 UCE (ES), Thunderbird 350 TBTS/NTB, Thunderbird 350 (2002), Machismo A350 and Machismo A500—all using the T1 CV carb system.

Q3. Does this O-ring fit BS6 J-Series or 650 Twins?
A3. No. J-Series 350s and the 650 Twins use EFI systems and do not have this style of CV carb float bowl. Use only on confirmed carburettor models listed in the compatibility table.

Q4. What symptoms indicate a bad float chamber O-ring?
A4. Common signs include petrol seeping around the bowl joint, strong fuel smell, damp carb body, and random changes in idle or tuning after heat cycles. If you see these, a new 500841 O-ring is a cheap, effective fix.

Q5. Should I add sealant with this O-ring?
A5. Ideally no. When the carb surfaces are clean and the genuine 500841 O-ring is installed correctly, extra sealant is not required and can even break off into jets. Only ensure both mating surfaces are clean and the ring is correctly seated.