Depends....


With temps between 5 and 15ºC I'll struggle to not going over 75-85ºC, the cold air cools too much the engine and gives you false readings. And people starts to lean it

Between 15 & 25ºC I'm pretty confortable between 95 & 105, 110ºC as maximum.

Over 25ºC is happy hour time, but I tune mine engines by ear and check the temperature only to assure myself that nothing is wrong there, doesn't matter if to go happy needs to go at 115 or 140ºC, each engine is a world apart and each one needs a different temperature. I have one engine that 'awakens' when temp reach 130ºC, under this temperature is a lemon.

Have seen one engine running happily at 150ºC.... each one is different. And the fuel you use makes a difference too.