I`m thinking about installing 4" risers on my 07 Roadstar. Does anyone know if I need to change my cables?

Can't say for sure on a rs but my strat is about 2 inch max. So I would say probably not.

If it is posture you are looking for you might look into installing Royal Star handlebars. Same length, less spread, but you sit more upright.

Dave

I don`t want to change the bars, just the height of the ones I have

I just looked at my '03 RS, and I'm going to say that you won't be able to get by with the 4". If they have a little bit of pullback in them then maybe.