AND save the little vent line, some of the Stihls have two itty bitty grub screws inside the vent line and you can use them on a replacement vent line later if necessary.
Do as Harley says and if the piston is not chewed up/scored get yourself a little squirt bottle and use 50:1 preferrably non ethanol mixed gas as a primer.
You can just leave the muffler off (but do not leave the muffler off if you get a run, kill the saw and put it back on and it's gasket and check the spark arrestor screen in the muffler while you are there, if it's clogged just throw it away) and prime a small shot on top of the piston instead of the carb throat if desired.
Too much prime and it will flood easily. Hopefully the piston is nice and clean with no major scoring, if the saws feels like it has a good jerky pull through type compression it should give a promise to pop and maybe idle for little while if it has ignition spark.
You can go to the Stihl site and download a owners manual for your 025 if you are not familiar with the saw, gives good info about how to normally start, etc. I mention this manual because Stihls can be flooded easily if not familiar with their combination of choke, no choke, etc.
Just leave the vent line off for now.
Good luck to you.
