You need to set yourself up as a CAD service bureau for custom chopper makers. Get all the model data from the engine, wheel, and frame makers, then design the custom brackets, etc. that the builders needs. Pretty soon, you'll have your own series, "American Chopperette".
Oh man!!! I could really get into that design job! All the time I've tried for jobs like that I never got any response at all. Would love to work on some kind of motorcycle or auto custom design team. *excitement shiver*