Can I get admission in BIT, Mesra for CS or mechanical branch with 102 marks in JEE Mains?

Please go through the opening and closing ranks here: http://josaa.nic.in/Result2016/result/OpeningClosingRank.aspx For the idea of the admission ranks for BIT-Mesra for 2016, the ranks do not change much for consecutive years, so you will get the rough idea.

I don't think you will get CSE branch but you might get Mechanical branch. All the best!