If they dont pump up then they are bled out tho there could be a slight amt of air in there that is hindering things but to K.I.S.S. it sounds like there ain't enough braking force at the wheels for whatever reason as it for sure should lock em up. would they lock up before the swap? What M/C What discs? Could get all 4 wheels off of the ground & idle it in gear & have a helper hit the pedal to see what the rears do and spin the fronts forward by hand & same thing. If air I'd bleed the M/C then rr/lr/rf/lf. On gravity bleeding sometimes you have to push the pedal a bit to get the flow started & doing both is the best.