What motor to run?

[Iain07]

hi, im new to the forum (so sorry if i say something stupid)
i've been having trouble with the motor that i run in my B4, i have tried skimming and re'brushing it but the top end speed is still far to low for my local track. i have also increased the gearing, with no real look.
i was wondering what motors you run and would recomend (for running at bury metro)
thanks for any replies
ps. am runnig the reedy kr 12T double.