Originally Posted by
earlwb
How long to you try to let the engine idle at? One doesn't really need to have long engine idle times.
I have a couple of .61 four strokes that didn't work right until I used 15% to 20% nitromethane in the glow fuel. Then those engines ran good. Before with 5% nitro glow fuel they didn't idle well at all. usually I don't have problems with low nitro or no nitro glow fuel in my engines, but I have a few that want more nitro in the fuel.
That's what I've read about a lot of engines, but unless they're that grossly under compressed, 5-10% nitro should be more than enough. You'd likely have to increase the idle speed to ~3,000rpm or higher. Smaller props don't carry as much inertia as a bigger diameter props.