Check out what someone did to a 2003 XR650L! Rather than motard the thing, they custom'ed it. :headshake
At first I was against such a project, but now the thing has grown on me. I mean it looks chopper-esque but it would still be pretty damn nimble (well as much as the L model can) and fun to ride. Can you imagine riding down the street on the rear wheel? I think only someone with a healthy dose of self confidence could handle riding this on the streets, but it definitely is distinctive.