I have a 1977 DT 125 frame and I was thinking of making it into a bobber style dirt bike, however, I want to upgrade it to a bigger motor. I figure the 125 won't be able to make much power. So I'm wondering what other motors would fit on the frame, maybe a XS 650 or something along those lines? any help would be great, thanks for any help guys!

I have a 1977 DT 125 frame and I was thinking of making it into a bobber style dirt bike, however, I want to upgrade it to a bigger motor. I figure the 125 won't be able to make much power. So I'm wondering what other motors would fit on the frame, maybe a XS 650 or something along those lines? any help would be great, thanks for any help guys!

Not really a good frame choice for that kind of thing. The backbone of the frame is relatively low/ the MX frame is worse so you can't do anything about the motor height. Maybe lower the bottom cradle but then you will have chain issues. Also the sheer weight of something like a XS650 will crush the life out of the DT sus.

Something 2 stroke is it really, DTR motor would be pretty easy as the lc frame isn't all that far from an aircooled frame bar the suspention and they are very tunable with big bores (see cardboard dave) Or track down one of the DT230 motors. Maybe go really nuts and squeese a dt400mx motor in there, or something YZ, bearing in mind the (hum)drum brakes.