While temps are not fixed to engine performance and model they are still a guideline.
Ideal is usually temps from 105 - 115 deg/c which is around 220-240 deg/f
Wouldnt want to run a engine any higher than 260 deg/f.
Look at your tune again, possibly just leaned out a bit much or you running a lean bottom end.
what plug you using can also affect performance and temp as well as what pipe/manifold you using.