kz1000 ltd carb help

I have recently picked upa 1979 KZ1000 LTD. It's a great running bike other than some carb issues. The problem I am having is that the rpms won't come down when i back throttle off. I can rev bike to 3-4000 rpm and back throttle off and rpms remain high. I have to hit throttle a couple times ant they will eventually come down. I diconnected cables and got same results. Checked carb mounts for air leaks, lubed vacuum advance, cleaned idle pilots etc. Checked accelerator pump diaphrams and they are great. The throttle is returning to idle screw completely and still rpms are high. It's worse when the engine is hot. I was thinking maybe a needle is sticking or a slide or two. If they where, would the throttle still return to bottom? It doesn't take much twist in throtttle to get the rpms to 3000 or so, so maybe the slide hang up is very slight. Any suggestions would be appreciated.

with the bike not running,twist throttle open and release.U should hear an audible click when the cable bottoms out and the slides close.If not something is hanging up,cable or the carb slides.bj

pods? pipe?....i doubt highly the slides are sticking as they are bolted to throttle shaft...if the spring is connected and yanking everything back,they are coming back whether they want to or not.....sounds lean....just my ramblings.....

Do your carbs leak gas? Roy

No gas leaks, tried with cables on and off and either way throttle always snapped back, I can hear it hit bottom and see it hit idle screw. I even had idle circuit screws running a bit on the rich side with no change. So much so that exhuast was getting quite black. Maybe I need to tear these carbs down and rebuild them. Might see something on the bench that I can't see on bike. Very wierd issue.

It's your ignition advancer!

Pull of the ignition cover, and then the ignition plate (after marking its location on the screws).
Unscrew the small bolt on the shaft and remove the advancer cam from the spring weights/arms. Clean the shaft and the cam inside with some metal polish very lightly. Then spray clean with carb/brake cleaner.
Coat both with light oil, like sewing machine oil and re-assemble.

Even though it may feel as though its returning properly, it must be very well oiled and clean, as once hot it can start to stick very easily!

GL!

If not already done, with engine running, would spray copious amounts of WD40 all around carb holders and vacuum plug caps.

Ingestion of the WD40 through an air leak should cause noticeable smoke from the exhaust.

Although an unlikely suspect, would also assure enrichener circuit is fully closing when the choke lever is pushed down to the off position. Could check operation of the choke shaft to assure the plungers are fully depressed when the choke is off.

Good Luck!

I vote for the vacuum leak as described by Patton. My LTD had the same problem when I first bought it. After jumping through all the same hoops the OP did, I finally yankd my carbs and discovered the previous owner somehow jammed the carbs back on, folding the number 2 carb holder over. It sealed sometimes, and leaked at other times. Talk about banging my head on the driveway! Drove me nuts til I finally found it.

So I cleaned, polished and lubed timing advance today, no change. Guess I'll be revisiting vacuum leak. I'll check plugs again as well and see if any are showing signs of running lean.

I am going to resurrect this topic since no resolution was mentioned. I am having the same issue exactly. I have a 2000 KZP...new carb boots clamped well to carbs and bolted to heads ( no leaks). no cable hang-ups. no ignition hang-ups. diaphrams good. slides free and clean. It happened after I pulled it out of storage from winter a few weeks ago...ran flawlessly last fall. Didnt drain carbs before storage.

Help is appreciated greatly