One of the possible problems for a machine not starting is fuel starvation. The first point of call therefore will be the fuel tank itself. Make sure that there is sufficient fuel of the correct type in the tank. (Always check the type of fuel required, i.e. unleaded or 4*). A common mistake is to use the wrong fuel. The other point to check is how fresh the fuel is-old fuel loses its capability to ignite as the octane in the petroleum evaporates over time. A machine not used for some time should have the old fuel drained and the tank filled with the correct fresh fuel.
Once cleaned the bowl can be reassembled, make sure that the gasket is fitted correctly to stop fuel escaping through the top of the bowl. Turn the fuel tap on again and prime the carburettor, fuel should now be seen at the overflow.