No matter if it's a stock motor or bronze axle bushings, they need to be polished to get the best performance. Just stop by your favorite automotive store and pick up some "Mother's" aluminum polish paste. Just force some into the bushing and run the motor or axle slowly for about 5 minutes. The polish will turn black while it's doing it's job and may need to be replenished once or twice. Make sure you really clean out and oil the bushings before you race.