Don't be surprised if you can only re-fill 3 Liters or 3,25 liters after an oilchange, there is oil sticking in the primary cover and some other places that does not come out with a normal oil-change. So always only refill 2,5 liters and from there, check oil-level and fill in accordingly. Even on a freshly assembled engine, sometimes only 2,5 liters fit in. Leaning the bike left and right sometimes fixes this and another half or full liter goes in. You should check oil-level after some kilometers after the oil-change again. It is normal that it lowers a bit as the oil gets distributed around in the engine. Don't overfill!!! This will raise the pressure in the crank case and will cause the bike to blow oil out of the breather. Stay well within the area between minimum and maximum!
Also make sure that you clean the mesh-type oilfilter that sits on the lower half of the crank case. You can reach it after dismounting the exhaust from under the engine, front, a bit to the left (3 nuts holding it). Finger around in the whole carefully after removing the filter to see if you find any bigger part laying around there (quite often, cam chain locking plates are dropping through the cam chain tunnel down there...).