when it melts, its too hot. u need to richen it up.

id say that high 200's is about the limit id like to run. if its really hot, a brush into the 300's isnt going to be catastrophic. but tuning for mid 200's a good pt to shoot for (as long as there is a trail of white smoke and clean running).

ive seen 350 a couple times. i shut it down and let it cool and then ran it some more after tuning it again. no problems.