thats a good tuning guide, but the problem is that it tells you to tune for some magic number. i can see the use of a temp gun for someone who is new, but just because your engine is over 260 doesnt mean it will harm the engine. i once owned an engine that wouldnt run worth cr@p until it got to about 300 degrees. that was with the needle still adjusted a little rich, so it was getting plenty of oil. although most engines do like to run in that range, some like to run hot, but i dont think it should frighten anyone if their engine gets hotter than that. (especially in hot weather, you will need to lean the high speed hence making the engine run hotter, but it should still get plenty of oil.)