VM 28 vs VM 26 carb- how to tell when on bike?

Is there an easy way to tell what carb I have on my bike? How can you distinguish the VM 26 from the VM 28? Of course I could just measure the diameter, but is there a way to see it from the outside? Thanks!

Here is the best reference I have seen:

www.z1enterprises.com/Z1CarbGuide.aspx

Great, thanks that helps!

Keep in mind, the Z1 page describes the differences between the VM28SC's that were on Z1s and the VM26SS's that were on KZ900s. I don't know what year for sure (maybe '78?), Kawasaki brought back 28s for the KZ1000's - VM28SS's that were very close to the VM26SS's (virtually identical I believe), except with a 28mm diameter instead of 26mm.

If they are not pumper carbs then...
VM28's have only the AIR screw on the side.
VM26's have only the FUEL screw underneath at engine side of float bowl.

If pumper carbs then ...
VM28's again have only AIR screw on side.
VM26'S have BOTH AIR and FUEL screws.

If someone has fitted GS750 or GS1000 carbs then both 26's and 28's have both air and fuel screws but no acceleration pump.

Ok now I am a bit confused. Mine are pumper carbs, but only have the fuel screw (and no air screw).

zed1015, that doesn't seem to fit into what you described or am I missing my air screw (don't think so, since I had the carbs apart). Photo attached.

Thanks!

WGCarbs.com is another place that may help in identifying what's what.

anotherZ wrote: Ok now I am a bit confused. Mine are pumper carbs, but only have the fuel screw (and no air screw).

zed1015, that doesn't seem to fit into what you described or am I missing my air screw (don't think so, since I had the carbs apart). Photo attached.

Thanks!

I haven't actually had any 26's in my hand as they are fairly uncommon and that piece of info regarding both screws on 26's may be incorrect although it was supplied by wired George on another thread so SHOULD have been accurate ?

However here is another SURE way identify the pumpers..
How many diaphragms on the bottom of number 2 carb?
If it's TWO then they are 26mm.
And if there's just ONE then they are 28mm (the casting for the second diaphragm will be there but not drilled or finished and will have no cap.

Looking at your pic i THINK I can see the cap on the second diaphragm ? which would make them 26's.

I just took another look and didn't see a second casing. But pls take a look at the photo and let me know what you think.

Ad thanks Martin_CSR, great link!

YES! They are 26mm.
You have one diaphragm with the arm attached which pumps the fuel and the other behind it is just a cap held on with 3 screws, this cap houses another diaphragm which runs off intake vac and shuts off the fuel to the accel pump when the engine is not running.
This is to prevent the accel pump being activated when parked and prevents flooding the motor.

26's have two fuel inlets while the 28's have one single fuel inlet I believe.

I have the VM26's on my 80 KZ1000 LTD

Now things start to make sense! My bike (1000 LTD) runs really well at midrange, but top end sucks.....which is characteristic for small carbs I believe.

I bought them off ebay as 28ss, learned another lesson here I guess!

The link that martin_csr provided (wgcarbs.com) says this, see below, now shall I ditch my set and find something else?

Note: 1979 KZ1000B LTD is fitted with Mikuni VM26SS with accelerator pump. These carburetors are essentially un-tunable and we hesitate to rebuild them because of their poor performance characteristics and will NOT perform on-bike sync, tuning and road testing on these carburetors. We suggest purchasing either VM26SS with no pump or VM28 with pump to replace these miserable carburetors