KZ1000 A vs. B VM Carbs

The carbs have been torn down and I'm now in the process of cleaning them up. Overall they are pretty good. The float valves look original and there is no perceivable wear on the needle so that's a positive sign. Both of the diaphragms are crusty so a kit is in order. The float bowl that houses the diaphragms is aluminum whereas the VM28 pumper carbs I redid had a zinc floatbowl in that application. I'll post some photos in a while so you guys can give me some pointers on how to disable the second diaphragm.

The second diaphragm needs to be completely removed, there is a drilling which supplies a vacuum to the second diaphragm i tapped it out to either a 3 or 4mm i cannot remember which size now and fitted a small grub screw in there with a wrap of teflon tape around it to seal it off, i then made a gasket and put the cover back on without the diaphragm, mine now work as the 28s solving the problems the 26's suffered with, you could just replace the carb bowls with a set from 28mm carbs, i will eventually replace the pumper bowl on mine with a 28mm bowl

I'm almost done with the carb restoration but torn as to whether or not to disable the 2nd diaphragm. If the carbs were going on one of my bikes I'd do it, but these carbs are for resale and as we all know, stock is highly desirable. Leaning heavily towards stock and listing the sale with the proviso that I'll disable the diaphragm at the buyers discretion.

And speaking of stock, what about jetting? The carbs came with huge jets, presumably intended for pods. How many KZ guys are using the stock airbox?

Nessism wrote: I'm almost done with the carb restoration but torn as to whether or not to disable the 2nd diaphragm. If the carbs were going on one of my bikes I'd do it, but these carbs are for resale and as we all know, stock is highly desirable. Leaning heavily towards stock and listing the sale with the proviso that I'll disable the diaphragm at the buyers discretion.

And speaking of stock, what about jetting? The carbs came with huge jets, presumably intended for pods. How many KZ guys are using the stock airbox?

How about offering them with the option of either mods? Eliminating the sensor diaphragm and selection of jets. Might separate you from other sellers. I’d make sure to add a disclaimer that any mods beyond stock configuration are at buyers beware. They are suggesting they the mods hence responsible for the performance or lack there of.

Nessism wrote: I'm almost done with the carb restoration but torn as to whether or not to disable the 2nd diaphragm. If the carbs were going on one of my bikes I'd do it, but these carbs are for resale and as we all know, stock is highly desirable. Leaning heavily towards stock and listing the sale with the proviso that I'll disable the diaphragm at the buyers discretion.

And speaking of stock, what about jetting? The carbs came with huge jets, presumably intended for pods. How many KZ guys are using the stock airbox?

For mine which i have jetted to suit the 4 into 1 exhaust and stock air box , i have 107.5 main jets and 20 pilots, fuel screws around 1and 1/4 turns out the rest is stock, i did try 17.5 pilots but found it a little on the weak side when on start up, a little popping and banging but it soon settled down when warm,

Vm26 Pumpers are the worst carbs on a Z and the least desirable in stock form.
I'd delete the triangular diaphragm as suggested and jet them to suit.
You can always include the unused parts in the sale with details on how to revert them back to stock if the buyer is daft enough to want to do that.

zed1015 wrote: Vm26 Pumpers are the worst carbs on a Z and the least desirable in stock form.
I'd delete the triangular diaphragm as suggested and jet them to suit.
You can always include the unused parts in the sale with details on how to revert them back to stock if the buyer is daft enough to want to do that.

As someone that has rebuilt quite a few VM carbs this comment strikes me as a bit harsh. The carbs themselves are identical to every other VM26 set other than the accelerator pump, and the funky 2nd diaphragm. I'm not a huge fan of the pump but it doesn't seem to hurt anything other than maybe make the carbs a little more leak prone at the squirt nozzles. The 2nd diaphragm seems to be the questionable aspect. It's not like the carbs are junk though.

If I was looking for a set of VM 26 mm carbs those are the last ones I would look at. And I would rebuild them to the 76 version if I could, or 77 if there is no fuel/air screw on them.

I think they have a couple of significant differences. Check the cutaway. And check if there is a fuel/air screw. Lastly, compare the needles and needle jets to earlier versions.

They have a pilot fuel screw.

Nessism wrote:

zed1015 wrote: Vm26 Pumpers are the worst carbs on a Z and the least desirable in stock form.
I'd delete the triangular diaphragm as suggested and jet them to suit.
You can always include the unused parts in the sale with details on how to revert them back to stock if the buyer is daft enough to want to do that.

As someone that has rebuilt quite a few VM carbs this comment strikes me as a bit harsh. The carbs themselves are identical to every other VM26 set other than the accelerator pump, and the funky 2nd diaphragm. I'm not a huge fan of the pump but it doesn't seem to hurt anything other than maybe make the carbs a little more leak prone at the squirt nozzles. The 2nd diaphragm seems to be the questionable aspect. It's not like the carbs are junk though.

You are correct, the second diaphragm is the questionable part, removed along with it's associated parts and vac port blocked off they run perfectly, they were a lemon used stock.

Nessism wrote: They have a pilot fuel screw.

They should be rebuildable to the '77 version. Or the early '78 version. But that 2 mm cutaway might cause idling issues. The original Zed''s had a 2 or 2.5 mm cutaway and were tougher to maintain at idle. Later Zeds used 1.5 mm cutaway.

Nessism wrote:

zed1015 wrote: Vm26 Pumpers are the worst carbs on a Z and the least desirable in stock form.
I'd delete the triangular diaphragm as suggested and jet them to suit.
You can always include the unused parts in the sale with details on how to revert them back to stock if the buyer is daft enough to want to do that.

As someone that has rebuilt quite a few VM carbs this comment strikes me as a bit harsh. .

Didn't mean to sound harsh but just stating the facts and certainly not saying they are junk by any means.
The 26 pumpers are well known to be the worst of the bunch in stock form and a pig to tune on anything other than in their stock application.
Once the triangular diaphragm has been deleted they are just fine though , much more tuneable and will be desirable to a wider range of buyers..