Having owned a Vulcan 900 for 10 years I've been involved in more tha a few discussions about octane. That bike called for 87 octane (USA Regular) and loads of owners wanted to burn 90+ because "motorcycles need premium gas". All of the research I've done indicates that you need to raise the octane once you hit around 11:1 compression. Since the 900 only developes 9.5:1, 87 octane works best. So my question is why does Kawi call out 90 octane for the 1700? I was surprised to see it also has a compression ratio of 9.5:1. Obviously I'm missing something.