Vintage Harley Davidson Motorcycles Porcelain Sign. Displaying an iconic blue, orange and black color scheme, this vintage porcelain sign measures 8 1/4″ by 6 1/4″, this sign is the perfect addition to any gas & oil or automotive-themed collection. Add this impressive piece to your collection today. This sign will enhance your mancave, collection, bar, shop, or garage. It is your chance to own a piece of Harley advertising. Vintage Harley Davidson Motorcycles porcelain sign. Motor Oil Quart advertising. 8 1/4″ by 6 1/4″. Vibrant colors and excellent porcelain.