KZ650B Swingarm Options for Rear Disc

I'm in the middle of building my KZ650B and want to convert the rear to a disc brake. I bought a KZ1000 CSR parts bike in the summer and stripped off both spoked wheels, the swingarm, and all of the rear brake related stuff. I was initially going to trim the pivot to fit the 650 frame and just us all of the 1000's rear end on my bike, but now I'm having second thoughts about extending the wheelbase.

If I were to find a 650SR, or another 650 model with rear disc, would the swingarm be a direct replacement? I've done some research and most of the advice I see being offered in that this swap SHOULD work, but never saw any confirmation to it. I realize that I'd still have to mount my rear MC somewhere on the frame, but was hoping to take the brake lever, MC mount, etc. off of the donor. Does anyone have any experience with this?

Also, for the rear wheel, my plan was to either find bearings that would with the ID of the hub and a 16mm axle, or just use the OEM size bearings from a 650 and have adapter rings built to fill in the extra space between the bearing and the hub.

Does it make sense to go with a 650 or the 1000 swingarm? I'm open to suggestions. I just don't want to get too far into this project and then realize that there was a better way to have approached it.

PS, I realize that a Zephyr arm is also an option, but I never see any available in my area, so I've just skipped over that route.

Thanks in advance!

Probably the closest match is the 650C. then the 650D. The 650D swing arm may be wider, since the SR has a fat rear tire.
What you can do is a part-by-part comparison at Partzilla. From a quick check of the B & C models, the swing arm sleeve & swing arm bolt are the same, as is some other stuff, including the needle bearings. Note: there are two different swing arm sleeves, but they may be interchangeable.

Thanks for the tip. I looked up the swingarm bolts and it's the same for both. The bushings are different, but that's because the disc models had needle bearings vs. mine with bushings. As far as I know, those are interchangeable. The swingarms on the C and D models seem to be different as well. Didn't think about that until you mentioned that fatter tire. The diagram shows a different torque link and it looks like the chain guard mounts are different.

78 650-B1
www.partzilla.com/parts/search/Kawasaki/...ABSORBERS/parts.html

78 650-C2
www.partzilla.com/parts/search/Kawasaki/...ABSORBERS/parts.html

78 650-D1 (SR)
www.partzilla.com/parts/search/Kawasaki/...ABSORBERS/parts.html

I would still like to know if anyone has actually done this swap. I've seen lots of later model single shock setups, ZR arms, etc., but would love to know if this C/SR swap is a pretty well a bolt in.

Eakin wrote: ................. The bushings are different, but that's because the disc models had needle bearings vs. mine with bushings. ......

Not necessarily true. The 1977 KZ650-C1 used bushings. Later models used bearings. Ed

My KZ650-C1 swingarm bushing parts.

Good point. I was only looking at the 78 models when I noticed that.

but would love to know if this C/SR swap is a pretty well a bolt in.

Yes, any kz650 arm will be your easiest swap.
Try to get as many spacers with the different model arm, and any brake components.
As you noticed, chain guards are mounted differently too.
Not a big deal, we don't need no stinking chain guards. :woohoo:

Awesome, thanks for the confirmation!
I'm hoping to pick up a parts bike so that I'll have everything available to do the job properly.

Hehe, exactly my thoughts with the guard. I was going to turn the grinder loose on those tabs anyhow. :evil:

PS, Rob, I just noticed that signature says that you're in Ontario as well. I'm in Toronto. Good to know that there are some KZ folks in the are.

I've been riding into Toronto quite a bit the last few years, and am planning to move back in this year.

I run chain guard less, and the tabs have been removed.
I didn't do it though.
I had a brace added to the swingarm, and he removed the tabs.