Gas Tanks & Fuel Accessories for Harley Big Twin Motorcycles. The Big Twin Gas Tanks & Fuel Accessories collection at TC Bros is designed for riders and builders seeking high-quality, custom solutions for their Harley-Davidson Big Twin motorcycles. This category features a variety of gas tanks, fuel caps, and mounting brackets that deliver durability, style, and seamless functionality. Compatible with models like Softails, Dynas, and Touring bikes, these components are perfect for achieving a sleek custom look or enhancing fuel capacity. With rugged construction and precision design, TC Bros gas tanks and fuel accessories provide the perfect blend of performance and aesthetics for your Big Twin build.