Hi
Do you have a temp. gauge to check the tempature?
You mainly want to keep these engines under 270-300 degrees f.
When I hear hot running, I think of bad fuel and/or a bad tune.
A good base setting to start from is flush with the collars on both needles.
On the low speed, to test for a good tune, you want to pinch the fuel line, and listen to the engine. If it imiedeatly dies, it is too lean. If it takes a long time, and increases in RPM dramatically, it is too rich. You want it so when you pinch, it takes 3-4 seconds for the engine to slightly speed up and die.
For high speed, run your engine around to warm it up, then make some high speed passes, slowly lean it out from flush on the collar (in about 8 deggree increments) untill you reach maximum performance. If you don't notice any power change after a while, or performance decreases, you are too lean, this is the most dangerous for an engine as it can over-heat and get starved of vital lubrication. In this instance, RICHEN the hsn (high speed needle) by ATLEAST and 8th turn.
You always want to have some smoke from the engine.
I consider (personal opinion) running my engines 200-250 safe.
But tempature is a second, if your engine runs perfect at 280, run it at 280, if it runs sluggish at 250 you rase it. See what I mean? Performance should be judged BEFORE thempature, but don't think tempature isn't important!
Hope this helps!