Royal Enfield E20 Kits for BS3 & BS4 Bikes

Royal Enfield has introduced official E20 conversion kits for its BS3 and BS4-era 350cc motorcycles, including the Classic 350, Bullet 350 and Thunderbird 350. The move comes as India accelerates the rollout of E20 fuel—petrol blended with 20 percent ethanol—across the country.

This update is particularly important for older unit-construction engine (UCE) models that were originally equipped with carburettors, as higher ethanol content can accelerate wear in legacy fuel system components.

Why the E20 Kit Is Necessary

E20 fuel contains a higher percentage of ethanol, which can be harsher on older rubber seals, gaskets, fuel lines and certain metal components. In carburetted BS3 and early BS4 motorcycles, prolonged exposure may lead to:

• Faster rubber degradation
• Fuel leaks
• Corrosion in metal parts
• Blockages inside the carburettor

The Royal Enfield BS3 E20 kit and Royal Enfield BS4 E20 kit address these concerns by replacing vulnerable components with ethanol-compatible parts. This ensures smoother fuel flow and long-term durability when using modern blended petrol.

Models Covered

The retrofit applies to older versions of:

• Classic 350 (BS3, BS4 UCE models)
• Bullet 350 (BS3, BS4 UCE models)
• Thunderbird 350 (BS3, BS4 UCE models)

These are the carburettor-equipped unit-construction engine bikes, not the newer J-series models.

Price & Installation

The Royal Enfield E20 conversion kit price starts at approximately ₹1,700 for BS4 variants. BS3 models, especially those requiring more extensive carburettor-related updates, may cost slightly more.

Installation must be carried out at an authorised Royal Enfield service centre. This ensures proper fitment, genuine parts usage and peace of mind. Since stock availability may vary across dealerships, owners are advised to check with their nearest service centre before scheduling installation.

Future-Proofing Older Royal Enfields

As E20 fuel becomes more widely available under India’s ethanol roadmap, upgrading older motorcycles is a practical way to maintain reliability. Instead of replacing a well-maintained Classic, Bullet or Thunderbird, riders can opt for this factory-backed retrofit solution.

For long-time Royal Enfield owners, the E20 kit offers a simple, affordable way to protect the fuel system and continue riding confidently in an evolving fuel environment.