Have a look at some good throttle control, the bike turns in great without throttle and then you pick up and add throttle once you've finished steering
Here is Yorik a UK based track instructor, listen to the engine and watch his throttle hand - great vid
Also, here's Simon Crafar demonstrating that you shouldn't have any throttle on until you've finished turning too.
https://youtu.be/-LXyNRRscc0?t=1m32s