Air cooled internal combustion engines...are hot. My take on too hot would be a ridiculous amount of pinging and shit coming from the engine, (maybe from shitty gas) and the powder coat burning away from areas around where the motor mounts to the frame. I think what you heard is a whole bunch of malarkey. If your ignition was too advanced, it could run hot. Without a temperature gauge on your engine telling you what your head temp is, how would one know? If you are really concerned about excessive heat, run synthetic oil in your engine and an oil cooler. You should try to maintain an oil temp between 180 and 230.
If you do a lot of sitting in traffic on a hot ass day, yeah, your engine is going to get hot. If your engine is running lean, yeah, it will run hotter than one that is running with the correct ratio. But to make a blanket statement that “Big Dog engines run hot”, some one is feeding you bullshit.... Tell them your full.