Well, I have never had a Traxxas engine, so I can't tell you exactly how far you should lean it... It does sound like your overheating the engine though. Yes, you could hurt the engine even if you see smoke...because overheating it is just plain bad for engines. If you don't have a temp gun, buy one, they are more than worth the money, then check your temps when running on the grass. I, due to my inexpirence with a Traxxas engine, can't tell you hot they should run as well, but I like to see around 220 on my other engines...