I´m somewhat of a newbie, but my friend has an older yamaha in his back yard with a blown piston (and an assortment of other cosmetic problems that a little TLC could fix), I believe it´s a Yamaha 175 DT from ´75, because its body style looks very similar. I´ve seen other years and they dont quite match up to it. I know it´s an enduro as well.
is 1975 the latest year they made the DT 175? if so I may have found all the info to get a new piston for it.