Topic: Will KZ1000 carbs fit on a CB750?

[westondc]

I found a CL post where the guy claimed that his CB750 Cafe bike has KZ1000 carbs on it. is this possible? anyone here tried it?

"1977 CB750 This has been my daily drive for years. I have raced it at Heartland of America Park in Topeka.
Very fun, fairly fast, always reliable, and has just the right looks.
VM28 carbs off of a KZ1000, K&N filters, and much more.
Head gasket last year, stator/regulator/rectifier last year.
I have had this bike for 5 or 6 years or more, but it's time to pass it along if I get enough for it."

[bucky katt]

ive been trying, unsuccesfully for a year to get some affordable KZ carbs for my 750.

[fishhead]

You will need the VM 29 Smoothbore adapters to put the KZ 900/ 1000 carbs (VM 26-28-29) on the CB 750.

KZ 1000 VM 28's on CB 750. The adapters are shown.

[Terry in Australia]

I've just bought some Mikuni 33mm smoothbore carbs on EBay set up for a later Kawasaki ZX1100 (from memory) for my 1060cc engine project, and are spaced closer together than the standard Kawasaki/Suzuki spacing so I'm hoping that they'll fit a CB750 head, but otherwise, Sudco can probably provide different racks and choke rods etc to "re-rack" them.

I had a set of 28mm Mikuni's that had been re-racked to suit a CB550, so with a bit of ingenuity and patience you should be able to make them fit. My CB750K2 has 32mm CV carbs off a later model Honda on them, the builder did a lot of engineering to make them fit, but they are so much lighter on the throttle than regular slide carbs, it feels like a modern bike! (and they'd be much cheaper than Mikuni's) Cheers, Terry.

[Free Booter]

You will need the VM 29 Smoothbore adapters to put the KZ 900/ 1000 carbs (VM 26-28-29) on the CB 750.

KZ 1000 VM 28's on CB 750. The adapters are shown.

You wouldn't happen to be selling a set of those adapters or know a place I can get some would you? I checked DynoMan and the site says they are on back order. I picked up a cheap set of kz1000 carbs and now want to put them on my bike.

I'd be willing to trade a buncha "extras" I got laying around...you're welcome to them if you can get me a set!
k5:
Side covers
grab bar
shocks
rear fender
rear turn signals
I know its not much, but I can;t seem to find any...
 

[Terry in Australia]

Sudco mate.    http://www.sudco.com/Carburetor01.html

[m in sc]

thats good info to know. I can actually lay my hands on a set of kz carbs pretty easy.
 on a side note i just moved the retun spring on my 78 carbs to reduce the pull. it is ridiculous stock.

[754]

I measured a set of what I thought were KZ 1000 carbs and they were about 28.8mm same as the  Z-1 carbs. spacing is 96 or 100mm and I think 240..
 78 CB 750 is 81mm and 233 mm..

[dtmmil]

I am in the process of swapping a set of CV carbs off of an 85 cb650sc onto my bike, they fit right into the 76 and older carb rubbers, the carb spacing is correct, or extremely close so they push right in, they take a choke cable like a 77-78 cb750, easy to work on, smaller, lighter, and like said the throttle pull is soo easy on them compared to the stockers. I am running pod filters on them for now, I can see that they should be adaptable to a stock airbox, may take a little work though.

And  m in sc, are you running a push pull cable on your 78? Just remember by taking the spring off, you have to always return the throttle.

[Free Booter]

Sudco mate.    http://www.sudco.com/Carburetor01.html

WOW! $164.85...
More than I paid for the carbs! lol'

So a list of advantages  Pros/Cons to the kz1000 carbs vs the Stock cb750k5 carbs?

Pros:

Cons:

??

[Terry in Australia]

Personally I don't think there's any advantage in fitting Z1000 carbs, they're still only 28mm, and are trickier to tune that the stock Keihins. Mikuni 29mm smoothbores are worth the effort, if you're going to hot up the engine. Cheers, Terry.

I am in the process of swapping a set of CV carbs off of an 85 cb650sc onto my bike, they fit right into the 76 and older carb rubbers, the carb spacing is correct, or extremely close so they push right in, they take a choke cable like a 77-78 cb750, easy to work on, smaller, lighter, and like said the throttle pull is soo easy on them compared to the stockers. I am running pod filters on them for now, I can see that they should be adaptable to a stock airbox, may take a little work though.

And  m in sc, are you running a push pull cable on your 78? Just remember by taking the spring off, you have to always return the throttle.

What size are they mate? Be aware that you need at least 32mm CV's to flow as well as the stock 28mm slide carbs, or it'll run too lean. Cheers, Terry. 

[m in sc]

And  m in sc, are you running a push pull cable on your 78? Just remember by taking the spring off, you have to always return the throttle.

i didnt remove the spring, i reclocked it a bit. about 120 degrees and made a diferent rest for the hook .it will return on its own very quick as it is, but i do have a push/pull on it just in case. thanks for the heads up though, good advice.

[Free Booter]

Guess I'll just keep waitin for Gnarlie Charlie to get some..I may send him my old carbs for a rebuild, but they are so shot..not sure what can be done (well at least 1 of the four looks a but bad.)  I used to rebuild carbas all the time for my bug, but too be honest...these days I'm just too busy and/or tired(read lazy).

[dtmmil]

Personally I don't think there's any advantage in fitting Z1000 carbs, they're still only 28mm, and are trickier to tune that the stock Keihins. Mikuni 29mm smoothbores are worth the effort, if you're going to hot up the engine. Cheers, Terry.

I am in the process of swapping a set of CV carbs off of an 85 cb650sc onto my bike, they fit right into the 76 and older carb rubbers, the carb spacing is correct, or extremely close so they push right in, they take a choke cable like a 77-78 cb750, easy to work on, smaller, lighter, and like said the throttle pull is soo easy on them compared to the stockers. I am running pod filters on them for now, I can see that they should be adaptable to a stock airbox, may take a little work though.

And  m in sc, are you running a push pull cable on your 78? Just remember by taking the spring off, you have to always return the throttle.

What size are they mate? Be aware that you need at least 32mm CV's to flow as well as the stock 28mm slide carbs, or it'll run too lean. Cheers, Terry. 

Carburetors
   
1983 - Four 29mm constant velocity
1985 - Four 32mm constant velocity
I got this from a website called pauls honda nighthawk pages. I have the 1985 cb650sc carbs, so they should be the 32s. I have changed the jetting, and other stuff since I added the pod filters, seems to run pretty good. Got them synced today, so I will see how it runs tomorrow.

[Terry in Australia]

Well done mate, and good to know you can buy "direct fit" CV's. Mine came from a mid 80's CBX750 and needed to be considerably "narrowed" to make them fit. Can you post a pic once you get a chance? Cheers, Terry. 

[dtmmil]

Will do.

[bollingball]

m in sc: Have you got any pictures or can you explain what you did to your return spring?

                               Thanks in advance  Ken

[MCRider]

I purchased and installed a set of VM29s back in 1980 or so. They came with the adapters. Unbeknown to me at the time was that they were stock on other models. I think i got them from Action 4s, which is no longer available. I told Action4s or whoever what i was running (888cc, head, cam, pipe) and they sent them set up. I just changed the Mainjet IIRC.

VM29s routinely go for $400+ on eBay and are no longer available from Mikuni new. I think.

The advantages were significant over K2 carbs. Problem is i had made alot of changes to the engine so hard to say what improvements came from the carbs and what from other things.

I think at least partially due to the carbs was first, more overall power throughout the band. Very even progressive pull. Less dynamic, but still important improvements were much quicker starting and warmup, less choke, smooth idle. I had no complaints. You have to run pods. There was the slightest murmur in crosswinds. Just enough to say hey what was that. I put 50,000+ on that engine, best ride of my life.

I'll be putting the same carbs on the current project. They used the stock Honda cables and everything. There was an issue with the fuel lines, resolvable with a T fitting from the auto store.

I think the 28s came on the Kawis stock, and maybe the last year they went to 29s. Anyway for the Kawi guys the 29s are the hot ticket. And at 1000cc, that would make sense that they work well on an 888c CB750. Z1Enterprises.com has some parts. On the Smoothbore page they have or at least used to have a legend "if you have any VM29s for sale let us know". I think Dynoman wants them too.

The Kawi guys take the 28s off so there are probably some of them floating around at a good price.

[MCRider]

VM29s, used, $405 and climbing:
http://cgi.ebay.com/ebaymotors/MIKUNI-SMOOTHBORE-CARBS-KAWASAKI-KZ-Z1-GS-HONDA-CB-DRAG-/180714137791?pt=Motorcycles_Parts_Accessories&hash=item2a1366e8bf

The 28s are cheaper and more available as they are the less desirable. As it was explained to me, and I am open to being corrected, the stock carb is a 28, but its an oval shape measured at the widest point. So putting a set of 28mm smoothbores on is an improvement as they are 28mm round. And just an overall better design. But as Terry says, and i don't doubt, they are harder to tune.

But to answer the original question, yes it is doable and has been done. I think both the 28s and 29s would be an improvement over stock. I'd had big engines before but never with carbs. So my butt reaction to the carbs carries some credibility.

The current CRs are the ticket, but i wonder if they are better than VM29s. The Mikuni VM29s are not eligible for AHRMA/Classic racing I think OCICBW, so less attractive to real road racer types.