there is no "magic temp" with these little motors....i've seen them scream all day at temps ranging from 170 all the way to 290+....the "rule of thumb" is to keep temps at around 230...i for one don't temp motors anymore, even for a base line....i tune by smoke and sound.......if your motor is still running rich, lean it out 1 hour at a time to where it's just barely rich until most of the mechanical pinch is gone from the piston/sleeve...then take it the rest of the way to a full tune...