I dont know at what exact point it comes off the low speed needle but it is after idle. Example would be I had a similar situation on a tight track where it would get really hot and lean bog, but when I would accellerate down the strait it had plenty of smoke. I found that the low speed needle was way lean. A good rule of thumb is always tune from a rich setting. After you find a rich setting on the low and high speed needle then start at the high speed needle adjusting 1-2 hours once it cleans itself out at the top end then adjust you low speed needle for punch. Once you have done all this the pinch test is a good test to see if your too lean. Just pinch the fuel line and the engine should wait 4-5 sec then raise the idle and die if it goes up right away your lean if it takes longer than 5 sec to increase then idles up and dies your rich but if it drives good alittle rich I would leave it there. Dont forget to do all this after the engine has heated up.