If i would have this prob. i would start to check the fuel availability. i.e. clogged fuel filter (in the tank, inline of the fuel pipe and if existing- at the etnry to the carb,)
If nothing found i would check the hight of the fuel level in the carb given by (dont know what it is called in english) floater swimming piece what ever thing .. which shuts off the small fuel valve with in the carb. There are dimensions available how to check this floater position.
Of course a week spark could cause this prob. as well. Easy to check this, right?
Good luck!
