ORIGINAL: RCCanuck

I ran without a temp gun for years....tuning can be done with sound,,performance and smoke trail with no issues......If you're really worried about it take a small medication dropper and fill it with water when the engine is up to temps drop a drop of water on the top of the cooling head and count how long it takes to sizzle away...3-4 seconds is about right....if it sizzles away faster its to lean.