Re: 1979 DT175 smoking
I would be surprised if it didn't smoke. If you run it enough to get it nice and hot, and do a few sustained full throttle runs, it will be less for a while, as you have blown all the residual oil out of the lower end; but unless it is making clouds of smoke, so much that you can't see, then that's what it is supposed to do. that's why no new two strokes are street legal anymore, and about not to be off road legal; too bad, they still pollute less than any diesel truck. But I guess that they are ok...
If you switch to Bel-Ray Si7 synthetic injector oil, you will find that it does smke a bit less, and no carbon build up as well. Drain all of the petrol based stuff out first if you switch.
There is a small bleed screw on the oil pump, usually a small phillips head witha red or black fiber washer under it as a gasket. run the engine, remove this screw, push the pully looking thing at the front of the pump with the cable attached to it from the throttle all the way in towards the pump body. look for air bubbles to come out of the hole. It should pulse as the pump plunger moves in and out, but no air bubbles. If (or when) good, replace screw, make sure it is tight. with throttle closed, a small pin or screw on the body of the pump should line up with a mark on that pulley. If not, adjust cable until it does. pump operates two ways: more pumps per minute as engine speed increases, and more of a stroke each pump as throttle is opened. That way you use what you need, not too much at low rpm/throttle openings as pre-mix does. The pumps are very good, just keep the air out of them and check the adjustments.