A copyright protects a literary, musical, dramatic, choreographic, pictorial or graphic, audiovisual, or architectural work, or a sound recording, from being reproduced without the permission of the copyright owner. The actual motorcycle itself is not copyrightable. A photo or drawing of it may or may not be depending upon who created it.
I don't believe a drawing depicting an image, which might be a Harley or any other product, is copyright protected. Certainly the Harley LOGO is protected, but not the image of what might be one of their bikes itself. A photo of a Harley might be copyrighted, but a drawing made using that photo as a basis may not be. When you make up such a cutting file just don?t be too specific in the exact details. Come up with one that might just "look something like" a Harley Davidson. Like this one: