I just got the yokomo D-1 Sports 27T (but no pinion gear so cant race it[&o]) but anyway it seems to jam, specially when in reverse, and bright sparks come out of the back area where the brushes are. Whats the problem? Bad motor, bad esc or me just asking a stupid question?

probably needs a com cut and new brushes.

A what? But its brand new..

then u prob need to break the motor in. search for the break in tut on this forum.

This one?

I've used the water method and it works perfect...

Yea i just finished braking mine in with the water method. Forward seems to work fine now but reverse still jams a bit, should i repeat the process but reverse the polarity so it goes through the procedure in reverse?