doesn't want to idle down after warming up???

hey guy's need some sugestion's..
just bought a very nice 76kz900ltd.. has 4-1 kerker,stock airbox... problem i'm having.. after warming up it idles fine,but when you rev it up to 2500 rpm's or so it doesn't want to idle back down,or it will idle back very slowly???
don't see any vacuum leaks or anything.. lubricated throttle cables. put new fuel lines with inline filters.
thought someone might have some simple checks for me???
thank's
just bought the bike thursday. enclosed pic for you to check out...

Not sure on exact specs on your bike but I would next check the ignition advance mechanism behind the points plate. Make sure it's clean, lubricated, and free to snap back to baseline timeing. Also check that timing is correct. If you are still running points, gap must be set correctly for timing to be correct.

Not a bad looking bike. I really like the turn up on that exhaust

it has dyna ignition... will check the advance mechanism..
when it's cold it will idle back nicely.. just doesn't want to when it warms up???
thank you all for your suggestions!!

My 650 acted like that. In order to get it to idle when cold, you had to crank the idle adjustment way up.

A couple of miles down the road, it would warm up I would have to pull over and turn the idle down.

I cleaned the jets and it is way better now.

Hope this helps.

Sean!
a big thanks for your suggestions!!!!!!!!! turns out it does have points after all... didn't even look like they were opening.. wasn't sure on exact specs. best i could recall 15thousandths would be pretty close.. once i found my feeler gauge which doesn't get used much gapped the points. fired up great and seems to idle better and will idle back after revving up now...
again a big thanks
vernon

Really glad to help! It's often the case that ignition troubles get confused with carbs and vice versa.

You still may have to check for the correct timing since the fiber tabs on the points have worn down. This may cause a retarded setting and you may not get full power. Grease the wick or cam lobes, I don't know what the 900 points setup has. With a timing light attached, rev the engine, and make sure the advance mechanism is operating. Just something I would do. Bob

How do you check the ignition advance mech ? I am having the same problem on my 76 KZ900.

BIGKEVIN wrote:

How do you check the ignition advance mech ? I am having the same problem on my 76 KZ900.

With a timing light, the advancer should move quickly back and forth as rpm is varied by blipping the throttle.

Sometimes the advancer hangs or sticks when it needs lubing, or both cleaning and lubing.

Good Fortune!

Is the advancer located behind the points ?

One way to do it, is with a timing light. Hook up the timing light. Start the engine, when you blip the throttle the timing should advance smoothly with rpm increase. When the the rpm returns to idle, timing should be base setting. But I just was thinking this might not be a good check if you are not returning to idle properly. Guess you are gonna have to do some disassembly! Like I said, you'll have to get specifics from service manual. I think you just gotta take the plate the points are mounted to off. Ignition advancer is behind there. Make sure everything is moving freely and the springs snap it home positively.