The easy way to tell how hot your engine is running is to use a temp gun. Cheap and effective.
Another way to get an idea is to drip a couple of drops of water on the cooling head...If it sizzles and bubbles and evaporates in 3-5 seconds, then it's about right.
If it beads up and jumps off, or evaporates instantly, then it's hot.
There should always be a 'healthy' trail of smoke from the stinger.(depending on which fuel...some smoke more)
---Even at WOT there should be smoke---