32:1 is not enough oil. The FG-20 uses 20:1

You are running a 125A cylinder. The bigger cooling fins on the 125B cylinder are the same as on a FG-20.

Horizon wants less money for a FG-20 cylinder than they do for a 125B cylinder.

The FG-20 cylinder has a higher compression ratio than the 125 cylinders.

The FG-20 cylinder has a smaller intake manifold than a 125.

They changed the 125 rod for the FG-20. They now use the FG-20 rod in the new 125's