I don't worry about engine temps. I listen to the engine and look at the exhaust. Once started, I lean it down until its just about to die (but with good 2 cycling) then add two to three clicks to richen it up . I then hold the plane nose up at a 50-60 degree angle to see if its leaning out. If not, you should be just right - not too rich and not too lean. It it tries to lean out, add another click or two to richen the mixture. If its too rich, teh engine will bog down. When your in the air, you shown see a slightly visible white exhaust stream. Then you knoe the engine is running just right. If you want a play toy in your flight box, buy a tach.