Normal range is 4500 to 5500RPM's, but I used to trim my 115 Yamaha up to 5800 RPM's lots of times with no problems, but it was on a 16' Checkmate and you could get a few more MPH when you needed to. I think 5500RPM's is a pretty good max to shoot for. Good Luck!
Why not look in your owners manual, if you do not have one then look at it online.
http://www.yamaha-motor.com/outboard/service/viewmanuals/viewmanuals.aspx?ls=outboard