Higher nitro content that burns hotter will require you to richen your engine sometime's on the low speed too. to do this you will need to turn your needle valves out a quarter turn at a time until its satisfactory. If it is a air bleed carburetor the low speed (idle) works in reverse. Another words turn it in to richen as opposed to out. So to lean out a non air bleed carb you should turn it in.
Most manufacturer's suggest you use 15% to break in and generally run 10%. Unless your doing high impact flying there really is no need to go beyond 10% but hey the higher the impact the higher the heart rate, lol. But you can get some really good sky with 5 and 10%. Hope this helps you remember.
Happy landings,
The Doc
-------------------------------------------------------------------------------------------------------------------------------------
OS .91 2 and 4 stroke, 2 a piece, G-2300, OS FS 70, FL 70, OS AX .46, OS 35, TTR .46, Super Tiger .45, Webra .61, TTR-.36 Evolution .46 Evolution Training system, Enya .40, TTR .61, OS LA Blue and Natural .46 and .40's and I know I am forgetting other's but I think you know what I mean.