Here's a motor you can run..................i've had a few of them, they're pretty decent and they are rated for 8 cells! This should "Speed the Pede"

Length: 2.26" (57.5mm) (can and endbell)
Diameter: 1.42" (36mm)
Shaft diameter: 1/8"
RPM: 25,300
Power: 144w
Operating Voltage: 4.8v - 9.6v

http://www3.towerhobbies.com/cgi-bin...?&I=LXLRE0&P=7