B7200 HST, 1640 Loader Lift and Bucket Cylinder PN

What to do depends on the location of the gouge and how deep it is. The picture makes it look like it was hit with an angle grinder. If you could buff it out where there are no sharp edges it might work fine. Is the gouge located where it passes through the seals? If not, it doesn't matter.

I had a cyl. on my trencher that had a scrape going down the tube several inches. The hyd. shop said it was no good and not use it. I took a piece of 3/8" all thread and attached one of those sanding disc that are about an inch wide and several layers of emery paper connected at the center. I used my variable speed drill to go up and down the tubing for several minutes. Polished pretty nice. That was 12-15 years ago. Still using it to this day.

I also had a slightly bent rod on a cyl., same machine, digging boom. I just reversed the entire cylinder. Then the curved portion was only passing seals when digging at full depth. Which wasn't as often and the other direction. Worked fine.

There are two gentlemen on the internet Keith Fenner (Cape Cod) and Abom79 (somewhere down south in the US)who are well equipped and who do cylinder repairs and lots of other repairs on all sorts of machinery. I have watched their videos and have not seen them do that type of repair but have seen Abom79 do what he calls metalising,

Before deciding to scrap your cylinder I would:

1 Talk to your local shop and hear what they have to say.
2 Send emails with your photo to above gentlemen and they may have suggestions.
3 Shafts come in standard diameters and if you could source a shaft (from a scrapped longer cylinder) your local shop may well be able to remove the ends from your shaft and weld/machine them on to the replacement shaft and put you back in business at cost less than that of a Kubota new cylinder.
Good luck

When I rebuilt my backhoe, one of the stabilizer rams looked pretty similar. I took it to one of the shops here in phoenix area that specializes in this exact type of repair- they turn it down, re-plate it with chrome, (.030 thick instead of the usual .003-.005 thick) then grind it back to original size. They repair all the heavy equipment cylinders in the state. The repair was perfect, but expensive.
($270) Last year, my buddy & I took a much smaller shaft from his Yanmar steering knuckle in for the same repair, & it was $495!!! The shop explained that the obama administration had made it almost impossible to perform chrome plating anymore- raising taxes, licensing fees, hazmat permits & disposal costs in an effort to kill the industry, as they had with lead refining & the ongoing attempt to kill coal in this country. They weren't sure how much longer they would be in business, and that most other platers were already in the area were already gone.
So I guess I'm agreeing with NIW- might be cheapest & easiest to just replace the cylinder, but I'd be interested to see one of the repairs mentioned if you go that route.

Just a note about the gouge in your cylinder. This may have been caused by the bucket stop (small steel block) that is attached to the loader forearm. I had a similar situation but caught if before the damage was done. If the drift pins that hold the bucket to the loader arms are worn they will cause the cylinder to hit this stop instead of the stop plate mount on the bottom of the bucket, and cause a gouge in the cylinder similar to yours. They don't have to be worn very much. Finding new drift pins is a bit tricky cause Kubota want your left arm for one pin.
Ron