if the ybr is anything like hondas cg125 they should be a small clip on one of the sides near the back wheel. most bikes dont have helmet storage except the "bike wanna be" Gilera DNA have you spotted it yet? thought not. where you expect the petrol tank to be is the helmet storage.
come on, someone must have some info on this version of the YBR, ok I know im new to biking, but cut me some slack. I really want that russian version and Ive never seen it in the uk nor is it advertised on the yamaha website the only picture they have of the YBR125 is: