z1classic with carbs

Z1class wrote: ...carbs...have air mixture screw no fuel mixture...It ran and drove fantastic so i took everything apart mostely for cleaning, put it back and now..It runs great until you close the choke, or if I put it in gear and let the clutch out it boggs down and dies under
3000 rpm. does this sound like a carb problem or something else.

Do the carbs have a side-located pilot air screw as shown in this pic?



Here's a method to clean the pilot circuit in a carb that has a side-located pilot air screw.




Good Fortune!

Check your throttle cable adjustment that could be holding the slides open

Z1class wrote:

Attachment 201144027.JPG not found

...still have the choke problem.

Guessing either 26mm or 28mm Mikuni manual slide carbs.

I don't know about the numbers Z12 00 and R 63.

To determine size, could measure interior diameter of bore where exits to engine.

In the pic, choke appears to be ON, because the plungers are in UP position.

Good Fortune!

Z1class wrote: Does anybody else agree with 17/117 . I said before it sat for ten years but the jets and gaskets look new, the p/o may have changed them he had somebody work on it a couple years ago. But never had it run rite. (i just learned this today) it runs about the same with
Air mix screws from 1 to 2 and 3/4 turns from seated. Would too small jets cause the need fore choke?

Another issue is -- what altitude is your home at? If you're in Denver, 5000 feet above sea level ("the Mile High city") then the air is thinner and you don't need as a big of jets compared to if you live at sea level. At sea level the air is more dense so you need bigger jets (more air at sea level = more gas flow required to avoid being lean).

I have on my '78 kz1000 the following jets, and it has the stock airbox and I'm at sea level in Silicon Valley:

20 for pilot jet
120 for main jet

My bike has a 'street baffle' Kerker and the intake side breathes a bit more air due to a modification, but it is close to stock.

My spark plugs are golden brown with this setup (at sea level, 120 mains, 20 pilots).

Compared to my nearly-stock-airbox kz1000, you are running MUCH more air into your carbs because you have individual 'pod'-style air filters (by the way those carbs look very similar to the carbs on my '78 kz1000)

And yet, you're running smaller pilots (117) than I'm using (120). If your altitude is close to sea level, you are flowing more air into your carbs with smaller pilots. Sounds lean for the pilot circuit to me.

At this point -- can you pull your spark plugs and take a photo of them or describe what they look like? As Patton has said, it really sounds like your pilot circuit in the carbs is too lean. If your pilot circuit was very lean, that would explain why you need to keep the choke open (compensates for the undersupply of fuel caused by the pilots being too lean and/or clogged).

Knowing what your plugs look like will be a big help to assessing where you're at, but unless you're at a high altitude, I think your pilots are way too lean and/or the pilot circuit is still clogged as Patton has described.

Did you physically remove the pilot jets and look through them to make sure they're clear? Typically if a bike only runs with the choke on then the pilot circuit is clogged.

I agree with Deers45 about your throttle cables being out of adjustment/routed incorrectly too. the instructions from Kawasaki are a little confusing and I never get decent results that way. What I do is loosen both cables, then adjust the pull cable until I have a slight amount of play in the throttle tube. Then adjust the push cable with about the same amount of play. check the throttle snaps back, if not, loosen the push cable just until it snaps closed.

Make sure the cables are lubed and double check for full throttle and full closed.

Thank you all that really helps. I have new spark plugs they are glossy black (not sutty) I am in the nw tip of washington at sea level. I just moved the bike from las vegas which is I think about 2000' but I had the same problem, but I had air leak on the booots then. Ive cleaned the passages as patton described, with compressed air too. Im going to try 20/120 and see what happens ive got 120 mains I just have to find some pilots. (choke is on in the picture) and it is a air screw on the side, havent measered the bore yet.
Thanks.

I forgot to write, I routed the cable how I found online, it has accelirator cable no decelirator. And I adjusted it as to my clymer book
with 1/8" of play. Thanks.

Did you adjust your air screw? I think you start at 1 turn out. One of the online manuals will tell you how to tune them.

Z1class wrote: ...new spark plugs they are glossy black (not sutty)....

If not already done, would perform the "clear tube test" to determine whether fuel levels inside float bowls are within specs.

A too high fuel level will result in excessively rich air/fuel mixture and black spark plugs.



Good Fortune!

What I did was hang the carbs level on an engine stand hooked up the gas tank, took the float bowls off and held a clear bottle bottom in place of the bowl. I checked two after adjustment with the tube the other two are cross threaded, didnt want to remove them. But the level in the bottle bottom and tube were the same about 3/16, mabey its just rich from the choke, but then it should run with choke off

Z1class wrote: What I did was hang the carbs level on an engine stand hooked up the gas tank, took the float bowls off and held a clear bottle bottom in place of the bowl. I checked two after adjustment with the tube the other two are cross threaded, didnt want to remove them. But the level in the bottle bottom and tube were the same about 3/16, mabey its just rich from the choke, but then it should run with choke off

What's cross threaded? Drain screws? Something else?

Good Fortune!

Yes the drain screws are cross threded so I dont want to take them out and strip them so thats why I used the bottle.