I'm not familiar with the logo.
But for similar patterns...ones I just can't seem to find, I check the web first. I look for the picture of what I want. Google Harley Davidson Logo under "Images." Save it as a picture. Print a duplicate. Sometimes I can just enlarge the picture with my photo editor.
If you need it larger than that, get is as large as you can. Carefully cut apart the elements of the design. Put each element on a sheet of paper and increase the size of each element by drawing and outline in dots around the outside of each element. Connect the dots.