Yesterday I was trying to set timing on recently acquired 80 Westy, but could not get it to run well. Points were good and I adjusted valves per manual. Still not running smooth and numerous backfiring. So I pulled plugs and ran compression test on all four cylinders
#3 & #4 had 120 pounds
#2 had 80 and #1 had zero.
I am not sure of problem, any ideas out there... burnt valve?, head gasket?, cracked head??
Also can the head be removed without pulling engine?

Anthony