Couple of battery questions?

[suicideneil]

120 is cool for a motor, no worries there. Gearing up may well lower the motor temp, and decrease acceleration a little, but then your topspeed will climb at the same time, resulting in an even harder to control setup. If the track is too tight to make use of all that speed and power, concider a slower motor (1600-1800kv range), or dropping down to 3s.