You should not rely on temperatures, only if you are not a good engine tuner. Although you should egt a temp gun. First tune your engine to performance. Start with a slightly rich setting. Then lean out the high end needle in increments of an eighth of a turn. Keppp doing it until you don't see a performance gain. Then richen by one-eighth of a turn. Make sure engine is wormed up befroe changing needels. Look at temp woth temp gun. Write down in a RC Journal what outside temp and engine temp. As outside temps rise the engine temps will also rise. Write down outside temps and humidity along with engine temp. Use that info for future tuning in same conditions. REMEMBER, ALWAYS TUNE FOR PERFORMANCE, NEVER ENGINE TEMPERATURES. I know what I am talking about I work at STAMPY'S COOL STUFF, it works every time.