I'll say '77 CR125 engine in a MT 125 frame.
Coil mount looks points type, and the steel rim and the shocks are MT'ish
That said it has a CR forged ally brake lever.
Pipe is from a 76/77 CR125 with the forward mount shocks. The head and barrel finning is 77 CR; different and slightly larger than the first models.
MR175 engines are different again and have studs and through bolts for the top end, not studs at each junction.