Hi, I've got an Hobbico hobbistar (RTF) with a OS engine 0.65LA with a 14oz fuel tank (I use powermaster 10%) and I get only 8 to 10 minutes of flight time, can someone give me some idea on how to get more flight time, is my engine isn't set properly or what?

I never flight with more thans 2/3 of throttle.

Thanks