I got 68MPG when I was breaking in the engine.  55MPG on average after that.  This is on a 2001 model.

Lean surge...(for the curious)

At highway speeds (60mph), my bike would surge.  I checked all the hoses and even ran it on prime.  Used some carb cleaner and it still surged.  I found out it was lean by slowly applying the choke.  At about half choke the surge would go away.  

After rejetting, it was better but not right.  I added one washer under each carb needle and it runs great.  Faster warm up also.  

Rejetting was the best modification I made.  Progressive fork springs are a close second.  Good luck.  

MacDuff