Wilton.com says that the motorcycle pan has been discontinued! But, it wouldn't work anyway to glue them together because they would have to face opposite directions to turn them around and match up...but great idea...maybe I can find a way to work around it. Thanks Agent.
How about using loaf pans...and stack two of them to get the height. You could use a plastic or wooden dowel, pushed in from side to side, then covered with icing, to make the handle bars. Just a thought!
Another idea. I have a book called "Creative Celebration Cakes". It has a picture of a 3D motorcycle. But you would have to carve you cake just as MrsMissey mentioned. It has step by step instructions.