The Losi motors will run hot anyway, they aren't as efficient as the Neus, the CC Neus, Hackers, Lehners or Medusas, so will produce more heat due to wasted energy.

As electric says, try other gearing options, gear down 1st, then if this makes temps worse, try going to a 13t and work from there.

Ill try experimenting with gearing over something like 3 minute runs. I know wrong gearing be it low or high will heat the motor. Should i still be looking for a thoretical 40mph speed even on 6s or does it change. Also what sort of heat tempo should i be looking at as being safe for the motor?
Thanks for the answers, the buggy is really good and i am impressed with it.
Jimmi.............

Always look for 40, no matter what the voltage.

Finally got a final today, 15 mins on grass (East Shrewsbury), did it with no battery change on a 4s 5000 battery and finished ok, didn't do any warm up or slow down laps and drove a bit "sensible" (cut down on the braking!), finished with 3.3v left in each cell. Was geared 14/45.

Happy I can get 15mins out of one pack, means I only need one change for even a 30 min final!

Your track obviously requires either less throttle, or you are just a smoother driver than I am, but that's an impressive run time for a 4S 5000 pack. I have had to move to 6S 6100mAh to get clearly over 20 minutes - and you can imagine the weight involved with that battery!