The AE.15x engine does run hotter than most. 260 and up isn't uncommon for that engine. Make sure the body is off for break-in, that will help with cooling a bit. What are you using to check the temps? I found out that the Duratrax tempgun is way off when using it on the non-annodized AE engines. However, if the temp reading IS accurate, then 300 is a bit too warm , even for that engine. Just have a little patience, take your time, and you'll be happy with the engine in the end. They can't be beat for the money. Hope this helps a little.