fuel delivery

KZ650 oem Mikuni manual slide carbs are more like these 24mm models.

Note the external horizontal ribs encircling the slide chamber.

Good Fortune!

Click on image to hear Bluemeanie say, Those look mighty familar.

Those look an awful lot like the rack of vm26's I had on my 77 650 awhile back. Although, the 26's and 28's look nearly identical on the outside, only way to know for sure is to measure the bore of the slide. I'd guess they are 26's, because as mentioned, 28's would be overkill unless the motor has been worked over real good.