Why?

hello!
1st question: why we usually find a capacitor at the motor of a radio control car? we want to increase the capacitance,and why this? for better compensation? an opinion?
2nd question: i want to place a more powerful motor.i must to increase the current?a simple circuit for this?
thanks!

The funtion of capacitor: noise filter for DC motor.
You need to know the semiconductor types in H-bridge circuit, consider the datasheets, maybe no need modification.

hi Zsolt!!! thanks,good summer!! )