1981 KZ440 ltd stumbles off idle

I think I have narrowed my problem down to the carb, and the fuel/air pilot circuit. I bought the bike recently with this problem. It idles ok, but pops and farts when rolling on the gas and runs fine midrange to top rpm. I pulled the fuel air screw and it had all kinds of white corrosion in the threads (florida salty air). I cleaned out that threaded area with chemtool spray and also all the jets in the float bowl. Problem persists. I think there is a blockage in the small tunnel between the float bowl and fuel air jet screw because it need almost full choke at low rpm. I have sprayed and sprayed, but I get no spray going thru there. How can I clean out that small tunnel? Is there a diagram of the fuel flow for the cv34 keihin carb somewhere? I switched carbs from my 82, which runs fine, and the 81 runs fine with those carbs. I compared all jet numbers and they are both completely stock.Thanks for any help.

Does the bike have the stock air filter hooked up? Ed

Both bikes, the 1981 and 1982 have pods and shorties on the exhaust. The carbs in the 1981 and 1982 have all stock jetting numbers, the same numbers in both carbs. But the 1982 runs great, and when I put those carbs on the 1981, it runs just as great. Something in this set of carbs on the 1981 is not working on the low end. The fuel air mixture screw has no effect screwed all the way in or out, that is why I think the fuel path from the float bowl to the pinhole under the fuel air screw is blocked. How can I clear that line in the carb? Chemtool spray and air is not working.

I should mention that the 1981 when I bought it had this problem, and it had stock exhaust and air box. I changed to the pods and shorties and the same problem exists. That's when I started digging into the carbs and found a plugged up fuel air pilot screw.

I have purchased a jet kit that has a larger main jet and washers to raise the needle a notch or two. I expect that will help richen it up midrange to open throttle and will install that after I get this blockage fixed. Once it is fixed, I may need to enlarge the pilot jet, but right now NOTHING is getting up that jet.

Could try this spray technique ---



Later carb designs didn't have the plug over the pilot jet or the tiny passageway. The plug is needed in a carb that's supposed to have it.

Good Fortune!

Thank you Patton, great diagram. I will try what you suggest. In the diagram where it says that the "spray should exit thru the orifice into the top of the bore" I get nothing there when I remove the pilot jet and spray directly into the pilot jet tube. I think there could be blockage right where the tunnel enters the pilot screw area. When I first removed that screw, there was a lot of white crusty powder (oxidation) in that whole area. I have tried fishing line into the pilot jet port but I can't get it to go all the way up to the pilot screw...1) should I be able to if it was clear?

2) Do you have a diagram like this one that shows the various jets?

3) I thought the pilot jet was the one next to the main, not the jet under the plastic cap. Is the open jet next to the main a secondary main?

4) Do you have any suggestion about how to remove a pilot jet that has been buggered up? I tried to remove the jet under the plastic cap on one carb but the screw end is damaged, as are the other jets, but I can get pliers on the others to remove. I would like to replace them all with new, but I can't get the one under the plastic cap out. I hope I am using the right names for the jets I am referring to....

5) What is that little "hole" that says "fuel to starter jet"? Is that the long tube that goes down into the bowl? I thought that was the overflow tube?

6) Can I purchase a new set of all stock jets for this carb someplace?

7) Final question...are the later model carbs available that do not have the capped pilot jet, that I could purchase and use? What model Kawasaki are they on and are they interchangeable?

Thanks for all your help...

If not already done, could also check the carb parts diagram at kawasaki.com, and If needed, here's a link for help with navigating kawasaki.com:
www.kzrider.com/forum/13-bike-related/37...imitstart=0&start=20

And also check the articles at:
kz400.createforumhosting.com/videos-of-kz400-f85.html .

May use the following link to download a manual that contains detailed diagrams of the various carb circuits:
home.comcast.net/~loudgpz/GPZweb/Mnls/Kz...ase99924_1018_06.pdf

Sometimes, soaking the frozen jets with Kroil, PJBlaster, Liquid Wrench, 50-50 mixture of acetone/ATF, or other penetrant for a few days might help loosen them.

If drilling out the jet is required, a reverse cutting bit may best help remove the jet.

Good Fortune!

Thank Patton. I am giving up on this set of carbs. I cleaned everywhere I know, sprayed into all the holes, put them on and problem persist. Runs terrible even on almost full choke on the low rpms. After it is warmed up, I put the choke off and it pops and stops. I screwed the fuel pilot jets out completely, held them in my hand and no change in the way it runs. Screwed them in all the way to the end and I did notice a slight decrease in rpm, but it still ran with choke on, I can't take the choke off or it just stops, even with idle set. I just got off ebay a set of carbs without slides. They say they came off a running bike. When I get them I'll clean them swap my slides in there and see what happens. I have been thinking about putting a mikuni VM34 on it as a single carb also. Time will tell...

An update...I got the used carb bodies delivered Friday and spent the weekend cleaning them and swapping my slides off the problem carbs. The used bodies were full of varnish, the jets blocked completely, couldn't even get fishline thru, had to use a small drill to push thru. I then I soaked the new carbs in pine-sol for about 4 hours and blew them out with chemtool, then with air. I installed my slides and new diaphragms (JBM rubber), installed the carbs on the bike and I think I am back to normal for a bike with pods, shorties and no jetting changes. It takes awhile to warm up, about 10 minutes, but then idles good after screwing out the fuel air screws about 4 turns. It runs strong but lean, popping a bit rolling back, sneezing a bit on low end. Now I can install the new jets, raise the needle with a couple washers. and see how it runs.

I've may have some used carb bodies for sale without slides and diaphragms if anyone wants to inherit some problem carbs!