Super 1's badass bike
 

Super-1's bike was custom made by Harley Davidson for the show. I believe that's the only bike made by an American company for the whole franchise!
The first episode, where he gets the bike, takes place in the US. Kazuya Oki is from the US, he's a scientist in the International Space Research Institute.

Someone correct me if I'm wrong, but I believe that Super-1 was also the first Rider to have more than one bike. Kind of makes sense, seeing as that Harley probably wasn't agile enough for a lot of stunt riding like the smaller bike.