Check the points,the coil,condenser,the wires ,plugs,after 4 years of sitting I'd give it a complete tune up and change all the above maybe just do an ohm test on the coil but if you're getting a yellow spark you may need a new coil.The battery could be bad check the voltage that also could be why you're getting a weak spark.
After that if she still is hard to start could be a fuel issue,change the fuel filter.And after four years might be a good idea to rebuild the carb.
Pete
