43cc engine wont start?

alright i have a 43cc engine it does have a key but somone lost it then gave me the scootter keyless. so to start the enginge you must pull the start then give alittle throatle and it starts. one day it was on and when my friend hopped on he gave gas it dyed now that i got it at home i cleaned out the choak and i even replaced it with a differnt one and it still doesnt start the spark plug is fine bc i took it off anouther scooter and test to see if both had blue sparks and they did. so i haave no idea i spray alittle gasoline in the spark plug holder then put spark plug back it starts for like 2 secs and dyes can anyone help me out