Insurance premiums higher for a Z500 than Ninja 500?

I've recently developed a major interest in motorcycles and am planning to take the beginner MSF course soon and buy a motorcycle early next year. I've already been checking models and my most likely candidate is the Kawasaki Ninja 500 or Z500. I decided to check how much insurance would be based on which bike I choose and found out something strange.

For the Ninja 500 it's 197 for basic, and 1200 for full coverage for the year.

For the Z500 is 263 for basic, and 2093 for full coverage for the year.

Does anyone know why that would be the case? I thought sport bikes would always have higher premiums due to them often being used by the type of person who would "take more risks". I just turn 28 if that could have anything to do with it.