The Genuine OKO versus Chinese Copies
The photos below were taken of both a genuine OKO 28mm K-101 carburetor (on the right), and one of the "better quality" Chinese copies.
The first give-away that the carburetor is a copy is that the Taiwan Flag on the box is replaced with the "K-101" sticker.  Actually, though the box is almost identical, the box with the copy does not have the "Made in Taiwan" flag even under the sticker
Once removed from the box, it appears that you are getting a better deal with the copy (left), as it includes a spigot adapter and extra jets, etc...
After the float bowl is removed and slide and needle are taken out, the differences begin to show up.  The pilot and main jets are not the same types and the shape of the lower portion of the jet block is also different.  Note, there are only two holes in the body to attach the float bowl.  This is not a problem for the stock bowl, but the optional clear bowl needs the two extra holes as seen on the genuine OKO.
In the photo above, the jets, main jet holders, pilot air screws, needles and slides are shown.  None of the jets for the copy (on the left) are marked, so it is very difficult to know what jet sizes, needle or slide you have.  The slide is also slightly larger, and the cutaway has a different shape.
In the photos above and below the slide for the copy is slightly larger.  It appears the the slide may have been copied and then chromed.  The copied slide will not fit in the genuine OKO carburetor body.  It is simply too big.
In summary, I am not going to tell you that the copy will not work properly.  It may.  However, even if you manage to get one of the copies "dialed in", the problem becomes one of replacement parts and knowing what jetting you actually have.  The genuine OKO slides are too small, the needle on the copy is unmarked, as are the jets, and the main jet and holder are not direct replacements for the copy due to the length of the needle jet the main jet holder screws up against.  One of the copies I purchased before making direct contact with the OKO factory actually had no pilot hole drilled in the carburetor body, so quality control is questionable to say the least. Though the OKO is said to be a copy of the Keihin, they have further developed and refined it and are producing a high quality carburetor at a very reasonable price.  The copies of the OKO appear to be others out to make an easy buck.