Yes,and it can be done on the side of the road with a piece of flat bar,string,rag,hammer,socket.I dont recommend those tools but we did that at a race track when we had a broken spring,,,,between rounds,,,
the string can be used in the spark plug hole to keep valve from dropping. Hammer and socket to take spring off. I recommend you use a spring compressor for reassembly. there is also a spring compressor that reaches over the spring and has a turn knob on top that compresses the spring and has claws,think of a steering wheel puller principal