gd4now wrote: Patton, I have posted some lists
kzrider.com/forum/3-carburetor/530034-jet-size#530036
and a how to ID carbs for the (K)Z650s (vm22ss and vm24ss carbs)that you posted above.
I am working (have been for some time) on a list of the larger (28vmsc, vm26ss and vm28ss) carbs but it is not complete as of yet. At least it is not in a state that I want to post yet.
I will say that info I can find regarding the 78 Z1R carbs the ID that should be stamped on them below the choke handle (though it could be on the same flange on the other side of the carbs) is 1040 and would look something like this
104
0 (could be other numbers or letters after this)
They are were vm28ss carbs. Keep in mind I am not at this point willing to say that is the one and only correct ID stamp, but it is what I have found to date. I also have found info that indicates the numbers you posted about the jets and internals to be the same other than what I have found indicates they had pilot screws and not air screws?
Okay, I've removed my 1978 Z1R carb jets (107.5 main jets found; 15 pilot jet found; etc.) and the carbs appear to be bone-stock.
And I found the ID that you guys are discussing here -- it is on the #4 carb's input side flange and is in 2 rows and it reads:
104
A
However, I did a web search on "mikuni 104" and found nothing. For anyone in the future reading this, I therefore wouldn't worry if your '78 Z1R stock carbs are stamped with something different -- there so far as I can tell is not a large enough significance with this stamping to reliably be able to ID the carbs, else I would think all the places I checked, including Sudco, would have mentioned it.
I'm thinking perhaps this "104 A" stamping might be a manufacturing lot code -- it may in fact specify a stock 28mm MIC carb but I haven't found any table that associates any series of numbers/letters with a specific Mikuni carb.
I'm hoping someone here will chime in and have a table that connects the "104 A" type of stamping with a specific size/type of Mikuni carb.
I'm satisfied though that I've got stock 28mm Z1R carbs here -- I used a caliper to measure correctly, at the intake side of the carb (thanks for the tip on where to measure Patton!) and they read 28mm, and I have all the correct stock jet sizes in the carbs too.