Metal fatigue

When I removed my rear wheel today, I discovered some metal fatigue on the back side of the rear gear, please see attached photos.
I don`t think these is any problem? but I wanted to check with you all.

The metal fatigue is not whole way around, but maybe 1/2 - 2/3 of total.

I have not found cracks going through.

Is it safe to use the part further?

I would change the bearing. All Balls has a kit with all three.
Steve

Thank you, my plan is to replace all three, but I was concern about the metal fatigue, you can see on the ALU its not clear on the surface?
Where do you find the kit with all three? I have used partzilla and order one by one based on part number.

Go to their site.
Steve

If you are talking about what looks like a million tiny cracks on the surface, they all look like that. I think it's from the casting process.

ahh... good news was afraid it was wear and tears..

Thank you.

www.partzilla.com/catalog/kawasaki/motor...ke-chain-81-82-h1-h2

1981 KZ650-D4 (The SR series of KZ650 was internally known as the Kawasaki KZ650D.)
European model.

When I look at partzilla I got a wheel with spiders but, I have ALU fix wheel, I`m not sure what you call it in English
So my questions, is the part the same when it comes to bearings?

I have also disc brake.

I have compared different models and it`s look likes the bearings is identical on different models around these years?
With or without disc brake etc.. ?

Is there a way can confirm these by using serial number on the wheel or something?

Maybe the best is to measure the dim. on the bearings I have ?

I think mainly casting defects - but I don't like the look of the micro cracks coming from the sprocket mount holes, a high stress area.

Without x ray or dye testing difficult to assess but I would keep an eye on it - certainly by next tyre change.

I had a really bad crack that opened up on my z1000R hub, and many years ago a rear caliper mount brake on me on the road.

Sometime ago I posted a similar thread on a gpz1100 clutch basket and the general consensus being quite normal.
Not so sure myself.

Normal.

Thank you all for your feedback, now I can sleep in the night