TOPIC:

I have another thread with some of my issues but I'm starting to think these are not the carbs that came on the bike. Looking for help identifying them and also validating which jets are where.



From this pic, according to what I have seen on here, these are VM24SS carbs. Has the ridges, doesn't have the extra inlet like the 22s. So far so good as the 77 should have those.

Now here is where things get weird.




This open hole should be where the pilot jet A/F adjuster screw goes. These carbs have the hole there but doesn't actually have threads and doesn't seem to have a circuit hole in there at all. So, because of that they don't seem to be KZ650 carbs



There is only one little hole, I'm not sure what it's for. From the diagram for the carbs with the screw down below it looks like there should be one after the slide.

So then there is this guy. According to the book it should be just a screw plug. However I'm left with this being my A/F adjuster, correct?



My last question is that there is the main fuel in, which is between carbs 2/3 on the bottom. However there is a smaller inlet ON both carbs 2 and 3 as well. I don't see what this is for in the diagrams. When I got the bike they were simply open. You can see what I'm talking about in the first pic.

For reference here is the manual, you can see where I'm expecting the adjuster to be as well as the air passage plug.

Those are the correct KZ650 Mikuni VM24SS carbs. The confusion you are feeling is caused by the fact that Kawasaki used three different flavors of those carbs, but the earliest manuals only describe one flavor.

The brass screw on the upper side of the carb which is marked "#16 air passage plug" in the diagram you posted is in fact not an air passage plug on your carbs. It is the "air screw" and it is used when tuning the carbs to control the amount of air in the air/fuel mixture. As it is turned counter-clockwise (out) it permits more air in the mixture making it leaner. My 1977 KZ650-C1 has the same carbs and I bought it new in April 1977.

The VM24SS carb in the diagram you provided has a "pilot screw" on the bottom; it's marked #5 in the diagram. I understand there were some KZ650's with that type carb, but I've never seen one in person.

The third VM24SS carb type had (sit down for this one) BOTH the air screw and the pilot screw! I haven't seen one in person, but I know for a fact they exist.

Later manuals included instructions for the air screw carbs you and I have. Here's some info from the KZ650-B1 / KZ650-C1 Kawasaki Service Manual Part # 99924-1001-01; Printed April 11, 1977>

Hard to say for sure they are original. From what I've gathered over the years all 1977 KZ650C model would have used air screw carbs like those pictured, but all 1977 KZ650B model used pilot jet carbs. So in my opinion if you have a 1977 650C they are probably original, but a 1977 650B they are most likely not original. 1978 they changed all to the airscrew type, with a small transition on the KZ650B where carbs had both air and pilot adjustments. All 650C used air screw carbs like pictured, but KZ650B depending on exactly when built used differing carb designs, but not that one in 1977.

RonKZ650 wrote: ....................From what I've gathered over the years all 1977 KZ650C model would have used air screw carbs like those pictured, but all 1977 KZ650B model used pilot jet carbs.................

Very interesting! The 1977 KZ650-C model bikes sold in the US were built in Japan. Do you know if the 1977 KZ650-B model bikes sold in the US were built in the US or Japan? If the "B" models were built in the US rather than Japan maybe that accounts for the difference? Ed

The open port between #1 & #2 carbs is a Vent port.
There is another between #3 & #4 (on carb 4).
The Vent ports should have a length of hose either going up and into the air box opening, or over the air box and clamped to the frame as shown below.
Do not connect the vents together, and leave the ends of the hoses open.

The carb connections picture above shows a Vacuum line/hose (green line) connecting to carb #2
Early VM24SS carbs ('77 models) did not use a vacuum connection, as they used a manual fuel valve.
'78 models switched to a vacuum fuel valve, and used a hose connected from carb #2 to the fuel valve for vacuum/air.

Not sure what the port is shown on carb #3 in your picture.
Is the port open, or closed?
I think it's closed, and used during making of the carb, then sealed.

1977 KZ650B was assembled in both USA and Japan. I think I was incorrect in my previous reply saying all 1977 KZ650B would be pilot jet carbs. Here's the info from Kawasaki:

KZ650B1 frame #000101-026990 was the serial number range of the made in Japan production, and 000101-016508 used pilot jet carbs, 016509-026990 used air jet type like the OP is working on.

KZ650B1 frame #500001-508015 was the serial number range of the made in USA production, and 500001-501185 used pilot jet carbs, 501186-508015 used air jet carbs like the OP is working on.

So later production 1977 KZ650 numbers, those are most likely original carbs. Seems like a lot of conflicting info on carbs over the years, but this is straight from Kawasaki on the topic.

Also no official mention of when the transition carbs that had both air and pilot screws were used. I would assume somewhere whithin short distance one way or the other from the numbers I posted. In my opinion, after working extensively with all 3 type, the airscrew type are easiest to work with. Pilot jet type can be a real pain, and the transition type are painful most of all due to the fact no one ever knew how to proceed in what order to set mixture screws.

I have used this link to id carbs before www.kawasaki.com/parts

First under category check (motorcycle)
Then (year)
Then ( vehicle)
It will give you very accurate drawings and parts numbers for that year.

If it doesn't look right try another year.

Here's the difference between Mikuni manual slide carb pilot circuits on the large fours, which perhaps is also applicable to the various KZ650 manual slide carbs.



Good Fortune!

Just to add more info regarding the carbs with both air and pilot (fuel) screws used this is from micro fiche

Kawasaki Service 4/600-11, 10/21/77
Recently the carburetors of the KZ650 were changed from the pilot screw type to the air screw type.
During the transition from one carburetor type to the other, several hundred units were equipped with
carburetors that had both air and pilot screws.
Units with transition carbs:
1977 KZ650B Frame # KZ650B024641-026991
1977 KZ650C Frame # KZ650C007751-010000
1978 KZ650B Frame # KZ650B027901-028701
Dealer action:
When you tune a unit with transition carburetors, turn the pilot screws all the way in. This will ensure
good idling and smooth running. The air screw setting is the same as the air screw type carburetors.
Pilot screw- Turn all the way in
Air screw- 2 +/- 1/4 turns out.

I do find it interesting that there is no mention of bikes frame numbers built in the US as having these types of carbs. Not sure if that means none had them or if they did the frame numbers were not included in this micro fiche?

Wow, sooo much good information posted on here. The 77 is a really odd year, I did alot of searching and was unable to come up with what you guys posted. Hopefully in the future others are able to find this thread.

RonKZ650 wrote: 1977 KZ650B was assembled in both USA and Japan. I think I was incorrect in my previous reply saying all 1977 KZ650B would be pilot jet carbs. Here's the info from Kawasaki:

KZ650B1 frame #000101-026990 was the serial number range of the made in Japan production, and 000101-016508 used pilot jet carbs, 016509-026990 used air jet type like the OP is working on.

KZ650B1 frame #500001-508015 was the serial number range of the made in USA production, and 500001-501185 used pilot jet carbs, 501186-508015 used air jet carbs like the OP is working on.

So later production 1977 KZ650 numbers, those are most likely original carbs. Seems like a lot of conflicting info on carbs over the years, but this is straight from Kawasaki on the topic.

My frame number is 502651, so it matches up exactly to the information from Kawasaki you found.