The Black Kat

I run a D5 11 single, purple springs, stock brushes and after 3 runs theyr'e a lil purple on the ends. Where should I set timing of the endbell and what brushes get good runtime & good performance (looking to get around 10 runs) I don't have a lathe...I have to use my dad's but he doesn't bring it to the track

I want the most runs possible yet I want good performance too.....I'll be willing to sacrifice a few runs if it makes it run noticably better