I just bought a 45MB, fairly original.
Engine compression is 1-90, 2-80, 3-60, 4-90#.
I'm hoping it is just carbon on the valves and will try cleaning with SeaFoam first.
I could not even find the # of Quarts it takes to change the oil?

I'm and amateur and any suggestions about trouble shooting low compression is welcome. Also, how many dern quarts does this motor take?!
Thanks!
pd