Two things:
1) Before fiddling with your carb, Did you ever redo your petrol pump? It could be that the pump is worn out and that it does not deliver enough feul to your carb. A kit does not cost that much and it takes about 1/2 hour.
2) You did not mention what type of carb it is, so it is a bit difficult to give more precise advice on what to do with the carb. (Remember, guys put all kinds of equipment on to their Landys, I for one have a Webber Carb on so it is no use advising you if you still have the old Solex carb on)
Regards