You should make the max temp you let your motor get to in a six minute run around 170-180 degrees. With you motor getting that hot that soon i would try going to like a 36 or 37 pinion and see how it goes from there, also check the timing on the endbell of the motor, on smaller track(sounds like a really small track) so much timing is not needed, that is like me taking my tekin rs and maxing the dynamic timing and running circles in my living room, do you have any pics or dimensions of the track, i could help alot more if i knew track size.