[chickentikka25]

Some things to try, in order of preference:

1. Gear down!! Put a smaller pinion on, say 2 teeth smaller at first
2. Check the timing on the motor isn't high - if it's anything but zero take it back to zero
3. Check your transmission is free and not binding at all
4. Don't run the car until the Lipo cut out on the speedo kicks in. 5AH is a huge amount of capacity at the end of the day so you might just be running far too long. And it's not good to take Lipo's to the cut off point anyway.
5. If it's a brushed motor it will feel hot anyway - check the colour of the comm and brushes. If they're even slightly blueish then yes, it is way too hot

If you're still worried about heat and it's a brushless motor, buy a £20 temp gun from Maplins and temp the motor after you run it. My B4 runs at around 45 degrees after a 5 min run which is perfectly acceptable. In my touring car the motor would come off at around 130 deg!

HTH.