I currently run this engine on a super hots with a os#8 plug and a 14x6 apc with 10 %. I have had this engine for about 8 years ... pulled it out of the ground on many occasions..lol...and it still runs like a champ...my current combo of fuel, plug and prop are about the best I have used with this engine. Tuning this engine can also be a pain in the rear. Start by setting your low speed needle...first, open the high speed needle 10-15 clicks from closed just to allow fuel to enter the car..then play with the low speed adjust till' you get a good idle..then open the throttle to mid range and open or close the high speed needle 1 or 2 clicks at a time and give the engine enough time to catch up to the adjustment. Once you are running steady there, open up to full throttle..repeat...it should be close to perfect at this point...if the engine drops off and stops it's lean and the HS needle should be open a few clicks at a time until it runs smoothly through the throttle range...if it runs erratic and spews tons of oil out of the exhaust it's to rich and the HS needle should be closed a hair or 3. Keep in mind that this engine will lean out alot in the air so a slightly rich setting is ideal for optimum performance. This isn't necessarily typical tuning protocol, but it's the best method I have devised for my engine over the years. It's not a fast ordeal and best done at home, not the field...so you don't use your frequency for long periods while tuning when another guy on your frequency could be flying.

Maybe you just need to involve your engine in several crashes first and just skip normal break in procedures....it seems that after each crash mine runs better...lol