Thank you. Maybe you are right.
I will give it more try and see what will happen.
I am going start from the 10L motor(no idea of the brand, but could be the same kind of Feigao),because it's chearper.
However, I have felt that the 10L motor is not as much torque as C50 Maxx .
ps.I have an email from Hacker USA. They told me to keep the motor in 165F and all should be fine.
However,I believe the 10L is not going to sustain higher temp than 50.