good temperature is where the engine works good.... you change the fuel, plug, propeller, and you have a different temperature, the day is cold, or hot, and you have another temperature, so it is pointless, just like a factory needle setting (only good as a start point!!). You will notice that the engine is overheated because it cannot hold RPM much, and looses power in a matter of seconds.... you will notice that the engine is too cold because you can touch it and won't burn your fingers in a couple of seconds, and won't deliver it's maximum power (too rich).


It is important that you change one variable at a time, to track the problem!


Saludos

Jorge