1/2A engines require a much higher nitro content to run properly. If you run low nitro (15%) they just don't like to run. Remember you are talking about engines with displacements of .049, .051, .061, .074, etc. For .10 - .15, I prefer to run 15% nitro, and above that it depends on the engine. My Super Tiger GS 40 is very happy on 10% while my OS .46 AX and TT .46 Pro run better on 15%. My FP .40 and LA .40 don't seem to care if they run on 10% or 15%, they just keep purring away.

jcervantes11,

When you set the idle needle 1/2 way through the bleed air hole, very seldom do you need to change that setting. My FP's have never been touched and they transition without hesitation. Even with weather changes I don't have to change them, just the high-speed needle.

Hogflyer