Idle problems

I am having idle problems on a kz900.At first start up it idles very low and stalls alot.But after warm up the idle goes up to about 1800 rpms.I then turn it down but it is still a bit erratic at about 1100.Any lower and it does not want to stay running.Acceleration is good.Could this be a sync problem or possibly dirty passages.I had the bowls off and replaced the needle and seats.Looks pretty clean,Any help would be great.Thanks.

KZ1911 wrote:

Could this be a sync problem or possibly dirty passages..?

You got it! :laugh:

Sorry your having issues, but you may have answered your own question.

It can also be caused by poor maintenence - hence, valve gap adjustments, small air leaks, no fuel filter/crud in carb pilot system, incorrectly tuned air/mixture screws, etc.

When the bike first starts up, it is not uncommon for it to idle somewhat low for the first minute or so - off choke. Some people use more/less choke, some just close it off and give the bike a few revs/minutes to heat up, but swinging up to 1800 is kinda high.

I would lean towards your theory more + Valve gaps.

dirty pilot jets /passages and maybe a vacuum leak.

Wrong fuel levels in the bowl made mine idle rough.