why is my quark getting so hot?

[gizzmo79]

I have som trobbel with my quark 125B.
In my revo I`m running with 4s8000mha and i feiago 8xl and 51/16-20.
When i have driven the car for 10 min or less the quark is realy hot in the end where the cabels to the battery are.
I don matter if i run with 51/16 or 51/20 is getting hot anyway.
Are the current draw to hige wite the 8xl on 4s?
I have tried with 2s and the 8xl, and that is not geting hot. But i got no top speed:019:
When i tried with a 8l and 2s with 51/20 the motor whas getting hot but not the quark, to heavy gearing?
Should i get a motor with lower kv? A wander 9xl is a 1662 kv, would that run cooler?