so I just pulled a 75 dt250 out of the bushes that one of our friends left at my place some 13 years ago running when parked but on a whim, I decided to fix it up and use it but I'm at the point of getting ready to start it up but I have no idea how the prelube system is set up and if I have all the parts iv seen videos of how it works but have no idea about cable/tube routing as my bike is in pretty rough shape and may not have all the parts I'm probably going to run it off pre-mix until I get it figured out but it would be nice to have it working

On the face of it i'd just premix it & carry on--forget the pump. Either take it off which is a bit of drama, so think i'd leave it alone & disconnect the cable so it pumps minimum stroke. Could remove the shims under the big plate washer that moves up & down which will cancel even minimum pumping stroke but even if the oil tank is empty the pump will still retain enough oil to keep things happy in the pump when doing nothing. Or cap it off & remove the oil tank [less weight more speed lol]. "75 will still have points ignition so hope you have spark & she lights up. Carb might be a mess but you'll soon know. At least drain it to get fresh fuel in there & make sure the throttle returns fully. Actually thinking about the oil pump--without the pump cable the throttle might be too light & unless the top cable is good & free it might not like returning without the pump spring helping it to pull the cable back down.

I'd drain the tank, fill with fresh two stroke injector oil, bleed the pump (just have to remove the bleed screw and let oil run out until air is out), and run the bike on both premix and the pump.

You can check the pump out later... the extra oil won't hurt anything... and you can send the pump to DEET to have it rebuilt.

Thanks, both the gas tank and oil tanks were empty when parked I appreciate the suggestions and will keep on working on it what premix ratio do you guys suggest to use?

I'd suggest 32:1 to start off with.

Mine didn't have the tank so I just premixed at 20:1 and jetted the carb to suit she loves it lol

Thanks!