I would think originally Victa had these without kick back it's just a lot of the mowers you get Norm someone has messed around with them before you get your hands on them. It;s just the amount of time you spend fixing them as I would just swap a complete motor that has a cast iron flywheel if you had one spare or collect one at the side of the road.
It's a pity you didn't hold on to some old flywheels when the last lot of engines went to scrap as they are quick to swap over ,the only problem with the GCV 160 is the 4 alloy bits that stick up for the starter so you most likely would have swapped to another starter cup and starter when swapping the flywheel.
Sometimes you hardly need any extra weight on the crank to fix the kick back problem ,a 250 gram blade plate hub can be enough to fix the kick back problem if your lucky.
Just swapped my GXV 160 alloy flywheel for a cast iron one ,it was only about 90 grams heavier but the cast iron one had 4 spokes going to the outer cast metal ring so most of the weight is in the outer ring and it seemed to make a big difference ,cut some grass that was taller than the mower and it didn't stall once also seemed to run smoother.
Pic below is a little difficult to see how high the grass was but there is an old car bonnet on the left side in the image and the bonnet is sitting on top of a mower so you can see the height of the grass next to that and this grass hadn't been cut since last summer.
I have heard the GXV alloy flywheel are a good replacement to fit on a GX200 as then you can disconnect the governor and rev them to 7000 rpm but you still need a few other mods first like billet conrod and stronger valve springs etc.The cast iron flywheel can explode if revved out too much also I hear the magnets can fly off.
