.ALL 4.2 stated brands use the Sachs/Makita 49ZN cylinder...TKG was correct, the cylinders are basically the same, just machined on the outside to look pretty...
NOBODY sells a 4.2 single with a different cylinder, there aren't any..PE made singles, inline twins and inline triples.. Some were glow, some ignition..Red and gold anodized cases...Brison cases are also anodized..Fox cases are polished...Some use Sachs cranks, some make their own..Sorry if you don't like the answer, It's FACT..Been looking at and repairing these for 18 years, starting with A&M and Lee Sachs conversions....
The 49 cast into the cylinder base is the bore size, 49mm..The stroke is 36mm.
Actual size is 4.1 cubic inches...The saw is a model 120 Super..
There IS a 4.2 Sachs, model 122 Super and 123..47mm bore, 40 stroke...
Specs from the Chain Saw repair manual, Intertec Publishing, 9th edition, page 452.