Actual motorcycle, actual sitting time -and actual oil in 'engine' that is likely a unitary design with tranny, clutch, crankcase as common casting. Might try a cold oil change, fresh batery or charge it, then try to start with clutch lever pulled back, back brake locked while on center stand. brake off, engine started and back wheel turning- pull in clutch lever and apply back brake- sticky clutch plates with fresh oil and dragging from rear may separate, be useable rest of season. Late 1970s sporties that had some of wet/dry clutch linings with newer light tranny fluid sometimes stuck after long over winter storage- that meant try the clutch lever in and back brake while electric starter tried to turn over- short lurch and freed clutch plates most times. Honda 450, 750 with abused clutch and stored sometimes stuck as well- try the starter with wheels up and then hit brakes couple times- worked 1/2 the time. Sporties niot that hard to get to clutch, separated plates and wash with bit of cleaner- or gas or some diesel. .