Need Advice on KZ650 Carburetors

After a lot of searching and reading about KZ650 carb swaps, I am now totally confused :S

I have a 78 650 SR (my next project) that needs carbs. I have a set of KZ1000 26's, a set of Z1 28's and a set of 900/1000 33 smoothbores. Will any of these fit the 650 and run well? The bike will be stock except for a header, individual air filters, and an electronic ignition. I think the spacing is the same but not sure about carb holder interchangeability.

Thanks!

id say the 26s would be more than up to the job.

None of them will fit the intake manifold rubbers. For that you'll need to change out the rubber for KZ900/1000 and slot the mounting holes to make them fit.

RonKZ650 wrote:

None of them will fit the intake manifold rubbers. For that you'll need to change out the rubber for KZ900/1000 and slot the mounting holes to make them fit.

Is the spacing the same? It's just the carb holder inner diameter that's different? What size are the stock 650 units, 24's?

Yeah, stocks are 24s. I'm just finishing up putting 26s on my 77 650 (just have to figure out the jetting and get them dialed in). You'll have to get the right sized intake boots (as was mentioned) and slot the mounting holes (quite a bit, I ended up having to slot them just about all the way to the outside of the boot). Use gratuitous amounts of silicone when mating them to the head and take it from there. Jetting them right will be the next pain, I haven't quite gotten there yet.
I would say the 26s would be more than enough carb for the 650 with the mods you're using. Any more carb would just suck more fuel.

So the spacing is the same then, good. You can't squeeze the 26's into the 24 boots? There's usually a useable range. For example, the KZ1000 "J" boots work for several sizes of the flatslides (34-38mm, I think).

Would you happen to know if any carb parts will interchange between the 24's and 26's? Like the tops and bowls, maybe? I might be better off using the 26's for parts.

I couldn't get the 26s to squeeze into the 24 boots for anything. And yes, many parts interchange between the 24s and 26s. I used choke parts, some internal parts and the top covers off the 24s because they were in better shape than the 26s. I did use a set of new bowl gaskets that I had for the 24s on the 26s so I'm pretty sure the bowls would probably interchange as well.

Yes the bowls and the spacing is the same. The big difference between the 24s and 26s is the OD of the carbs going into the intake boots. If it was really only 2mm or so as you'd expect, the 26 would probably fit, but the difference is larger than that. I measured a few years ago and of course didn't take note, but I think the difference was between 3-4mm larger on the 26mm vs 24mm. Also the other end of the carbs is larger as well, so you can't use stock 650 airbox or 650 size pods. Easiest to use KZ1000 pods.