There are a couple of options

vintage motorcycle or fresh off the showroom floor

A reproduction of the Lucas tail light found on many British motorcycles of the 1960's

and one for early cable clutch cables

1/4 inch NPT Mini Petcock 90 Degree Outlet - No Reserve Subcategory_Clutch There are a couple ofThese 1 4" NPT mini motorcycle petcocks have no reserve and feature a solid on off ball valve for a long, reliable life. These small petcocks tuck up under your gas tank for a real clean look. Features a 1 4" NPT thread on one end and a 90 degree outlet with a 1 4" hose barb on the other. Rugged steel construction with Zinc plating. Viton O ring stands up to most commonly used fuels. Sold individually.