Also remenber that when you reverse a brushed nonadjustable timed motor that
you loose some rpm's because most have the timing advanced a few degrees
to run in there forward direction , if the timing is set at 0 degrees the motor will
run the same rpm's both direction but not have full rpms that its capable of
producing
The more advance the timing is , the more rpms & less low end torqe it has ,
its not a very big deal as the torqe has moved a tad higher up the rpm range
in the forward running of the motor

This basic info is for why you wonder why its got more power running one direction than
the other on a brushed motor & you reversed it from its normal running direction

Hope this explains a little of whats going on & not to confusing
Now brushless is a whole different ball game