TOPIC:

Hello, I have a carburetion problem with a Kawasaki KZ400-D3. The idle is totally unstable, with rises up to 4000 rpm and descents to a complete stop, without touching the accelerator. I have tried starting both cylinders separately, and they both have the same problem.

The most curious thing about it is that the idle was PERFECT until it occurred to me to open the carburettors to clean all the jets well and change some o-rings that were cracked.

The matter drives me crazy. I have a lot more work to do on this bike but I'm stuck on this and can't continue. Where do you think we should start to check?

I have just disassembled them and I have noticed that the pilot plugs (which I also replaced) are somewhat longer than the previous ones (which were rotten) and it occurs to me that they might obstruct the hole that connects the main passage with the pilot passage.
My question is, could this supposed hole obstruction cause that totally unstable idle and also self-throttle?

Thanks.

I finally found it. The problem was in the pilot plugs, I made new shorter ones from O-ring thread (6mm, same as the originals), I assembled everything and the miracle happened. Perfect idle and response, now I can continue with the restoration.

I hope it helps if the same thing happens to someone, thank you very much.

wrote:

I have just disassembled them and I have noticed that the pilot plugs (which I also replaced) are somewhat longer than the previous ones (which were rotten) and it occurs to me that they might obstruct the hole that connects the main passage with the pilot passage.
My question is, could this supposed hole obstruction cause that totally unstable idle and also self-throttle?

Thanks.

gonna give this  a go. i just got this bike a couple days ago. tweaked with the idle to get it started but same problem. hits 4 and kills out.