As lovely as the original fuel taps are, they can be a pain in the bum as evidenced by the number of clothes pegs you see in their near vicinity on ageing bikes.
Distorted tanks and misaligned fuel valves are an even bigger problem because it can result in a fuel leak, and this little fella has been designed to fix that particular problem.
Basically, you replace the standard valve seat with one of four inserts – depending on whether you want to use a 1/8–inch NPT, 1⁄4-inch NPT or 22mm petcock. It has been designed retain the original crossover line and the included cap can close the top of the tank. No more puddles of fuel, and a reduced fire risk.
Bates 1940-’65 Fuel Conversion Kit:
W&W 36-342: CAD (ZnNi process) for 1/8-inch NPT petcock €55.60
W&W 36-393: CAD (ZnNi process) for 1⁄4-inch NPT petcock €51.10
W&W 36 392: Parkerised for M22x1 petcock €26.91
W&W 36-395: CAD (ZnNi process) for M22x1 petcock €51.10
wwag.com

