You can lose 30-40Kgs from the kerb weigh with some effort.It includes putting away the fairing(for and aerodynamic one) the lights and indicators,chain guard,front mudguard,speedos and all meters,lighter and small fuel tanks,smaller seat but maybe not accomodating rear passenger(who races with a pillion!) and the extreme like drilling hole in chasis and swing arm,crankcase.This is a universal weight saving for formula
Engine would need a shaved head for high compression porting and polishing job,along with a (optional)bigger bore and a tuned exhaust with a high flow filter with upjetted or flat slide carb.
Main time is taken by engine.........Cg 125 is not in India but we have 125cc bike and though they are not raced,bigger 150cc and + bikes are raced and motors run up as high as 180-190cc are produced.