Ask about Tamiya motors for xmods

[TreeFlash]

hi guys ... I want to ask ..
recently i bought a new motor tamiya ultra dash and hyper dash 2, when I try the ultra in my evo xmods. the xmods direct his heat and did not until two minutes played a direct battery runs out and it happenent again when I try hyper dash.
so the question is, do I need a capacitor in the motor like the stage 1 stock from xmods? If yes, what the size of capacitors for use in ultra and hyper dash?
thanks ..