My 1992 xr250l sat for a couple years. I've cleaned the fuel system twice and installed new pilot screw and set at 2 1/4 turns out. Everything is stock 38/122 jets on Keihin 79g carb. I have to open the pilot screw three turns further to get the bike to run a bit better but it still needs partial choking and stalls without it. I'm afraid the pilot screw is going to fall out if I open it any more. Help. Mel