Upgrade your Royal Enfield Thunderbird 350 BS4 with the UCAL Original E20 Carburetor (Part No. UCD29-16-E20). Specifically engineered for E20 ethanol-blended petrol, this genuine OEM CV carburetor with integrated TPS delivers smooth throttle response, reliable cold starting, stable idling, excellent fuel efficiency, and perfect direct fitment for long-lasting everyday performance.