core stock
Pro4,
Ritchie is right about the com size and springs, the core stock works better with the com cut down and yeilds its best performace in the 270 to 280 range. Sping wise double reds do work best but non the orion reds use the 9oz trinity ones instead. I did some testing a couple months back with an old core I had and found that the motor performed best with F brushes, verticle cut on both. Other brush setups that worked well were: 4503 pos verticle cut w/ 4499 neg .050 hole, XXX full face (no serations) with a .050 hole in both.
Mark