I would say that it is time that you clean the carburettor, likely the high speed nozzle of jet is partially clogged.
Or the air filter could be dirty and blocked,
Take it off, clean it in a container of petrol (gasoline) , rinse it in warm water and detergent , let it dry completely. Oil it with genuine air filter oil.
This should be done every couple of thousand kilometres or after every day of offroad dirt riding.
Hope this helps.
my bike starts but when i turn off choke a hair it dies Why??