Do you have stock carbs? Tors? A banshee can run on one cylinder, so you got to determine if both cylinders are firing. I would check the reeds if the bike has been sitting for that long. If your sure the carbs are clean, floats working, needle valve/seat are all good, air filter clean, then I would do a leakdown test. Then a compression test. Check and clean ground wire. Check both plugs for fire. Good luck