Different year/model 650's use different axles and different bearings, and the 440 is "probably" the same way (I don't know for sure about the 440).
If you look in the FileBase there is a list of what wheel bearings each model uses, and if both bikes use the same bearings then the axle diameters are the same.
I just looked at the Filebase article, and there are two different front wheel bearings, and two different rear wheel bearings, for just the KZ650. The KZ440 is not listed, but the same thing applies to the 400.
So without more info, an accurate answer is not possible.
If you have the wheels off the 440 then you can look at the bearings and get the numbers off them, and I assume you have the KZ650, so posting the year and model for that one should not be to hard.
Generally speaking (pretty much always), you will not be able to just swap the bearings, if the ID is different then the OD will be different. If the 440 axle is smaller (and you have it) then you may be able to make a sleeve to go over the axle and inside the fork clamp. Or you may be able to have the center of the wheel (where the bearing goes) machined to increase the diameter so you can use the 650 bearings. I think that "adapter" bearings may be available as well, as some people have used inch bearings to replace metric bearings and got a reasonable close fit (But I am not in favor of "reasonably" close on wheel bearings).
As far as the rear wheel, are you switching from drum to disk, or disk to drum, brakes? Again, a little more info would be helpful.
Post edited by: steell, at: 2006/05/01 17:13