No. Its not liquid cooled and having (i think) a head stud showing at the back of the head its a 175. 6 studs for 175, 4 for the 125.
Dependant on the side the oil tank is on and if it has a round or square section sw arm will date it.
As is its a 1979/80 ish Yamaha Dt175MX. The 125 is litterally identical bar a clutch plate,bigger bore and 4 or 6 head studs. Easy upgrade, or in my case down. I will be making my 175 a 125 for my daughter.
Put the first half of the engine/frame number up and we can say for certain.