Z series Kawasaki Service Bulletin #SER 74 Z-31 dated 5-27-74 documents the changes to the carbs beginning with engine # Z1E-032866.
The (old) asymmetrical float # is 16031-024.
The (new) symmetrical float # is 16031-028.
Carb body ID #'s:
(old) 147 0, or 147 1, or 147 2.
(new) 217 0.
The following carb parts were changed at the same time:
Needle jet (P-8) #13017-064 > (0-8) #16017-086.
Needle jet holder 16047-002 > #16047-003 (different dimensions).
Pilot jet (#20) #92064-035 > (#17.5) #92064-042 (different dimensions).
Throttle valve (2.5 cutaway) #16025-051 > (1.5 cutaway) #16025-075.
Float bowls (large drain plug, all 4 cylinders) #16020-015 > (small drain screw) #16020-016 for cylinders 1 and 2 only. #16020-017 for cylinders 3 and 4 only.
Fuel level gauge:
(old) #57001-122
(new) #57001-208
We realize that this doesn't address the post-76 compatibility question, but perhaps will be helpful anyway.
EDIT 1: - KZRider.com continues to fail with a 403 error code when we attempt to access it only from home with Firefox or any other browser. The obscure browser/VPN workaround we have to use for KZRider doesn't often play nice with attachments. Don't know why. We posted the referenced service bulletin as attachments in both .pdf and .jpg. but cannot tell if they're visible to the members.
73z1, if you cannot see the service bulletin please send us a PM with your email & we'll send it to that way.
EDIT 2: We can see the .jpg's correctly, but not the .pdf's. That's progress of sorts If anyone can see the .pdf's please let us know via PM.
Good Ridin'
slmjim & Z1BEBE