I have a pair of K&B .65 Sportsters. The sportster engines all run very well if ran on the right fuel. Most airplane fuel at retail stores is going to be a synthetic blend or all synthetic. These engines do not like these kinds of fuels. Its best to run an all-castor fuel with no more than 15% nitro. My .65's run hot on 15% nitro and performance is about the same on 10% nitro 20% oil (half castor half synthetic) I've heard they run best on all castor fuel with little to no nitro.

My engines are from military drones and need the idle disks changed but will swing a 13x6 or 13x7 prop easily. That .45 should be able to spin an 11x6 or 11x7 well.

Is there a remote needle or is the needle on the carb body? The newer sportsters have a remote high speed needle which uses an idle disk but not an eccentric screw (if I remember right). If the main needle in on the carb body, the eccentric screw doesnt change the idle mixture much - it only moves a little bit in either direction. With the Eccentric screw centered, clockwise richens and counterclockwise leans the idle mix. Start it in the middle and run it until warm. Set the high speed mixture to peak RPM and richen 2-3 clicks THEN set the low-speed mixture. The low speed mixture controls the fuel mixture up to about 3/4 throttle. If it transitions from low rpm to high rpm real rough and smokey, lean the idle disk about 1/4 of its travel.

These are good, torquey 2 stroke engines that will swing bigger props than would normally be ran on an engine this size.
Hope this helps.