Engine not returning to idle correctly
 

I recently purchased a 1997 Kawasaki 600 ZX-E. The previous owner had ridden it about 2 miles since last season. The engine is revving up very high and taking a long time to get to idle. The initial thought was that the culprit was the throttle cables. The throttle cables were removed, lubed with WD-40, and everything was put back together. Before putting it all back together the throttle cables were snapping back very quickly as they should. The WD-40 leaking from the throttle cable ends after running it through was not rust colored or discolored in any way. After it was all back together and we believed it not to be the throttle cables, the idle adjustment was played with. The idle adjustment was played with until the motorcycle was idling at 1000rpm. The idle didn’t sound completely right. It gave a sort of puput-put-putput-put as if something was missing. However at slightly higher rpms it seemed to sound fine. The engine could be throttled up to 6000 or 7000 rpms and would slowly subside and not quickly go back down to idle.
Does anyone have any suggestions as to what I should do next?

RE: Engine not returning to idle correctly
 

i would suggest cleaning the carbs and checking the diaphrams are good. then sink the carbs.

RE: Engine not returning to idle correctly
 

+1^ and check for disconnected vacuum hose/s. Spray the throttle slides with carb cleaner or WD40.

RE: Engine not returning to idle correctly
 

Where should I spray to check for a vacuum leak? And what will the symptoms be if there is one?

I tooled around with the bike a bit last night and it seemed to be ok (once warmed up) when I would let the clutch out above 2000 rpms. Anything less and the bike would shudder and studder and if it didn't stall it would eventually get going. At around 3000 rpms it would surge with power. Is this just due to the power curve or is it more indicative of one of the previously described problems?

RE: Engine not returning to idle correctly
 

you will need to spray the carb cleaner around all the vaccum lines and intake boots from motor to carbs and carbs to air box. that will let you know if you have a air leak when its running and you spray it should kill the motor right away. from a idel applying gas not in gear how does it rev up?

RE: Engine not returning to idle correctly
 

If it bops down to idle from RPM than it's usually the carbs. I would check the vac lines too.

RE: Engine not returning to idle correctly
 

Drain the carbs too.

RE: Engine not returning to idle correctly
 

Im having the same problem with my 97 zx6R. When I cold start it, the RPM's jump up to 4k and I have to take off some choke to get them back down. And when I come to a stop quickly my RPM's lag a bit, they dont drop back down to idle speed they just kinda get stuck at about 3k. Does anyone know what could be causing this?

RE: Engine not returning to idle correctly
 

Check your cables, return spring and vacuum lines for leaks/ cracks. Usually at idle, if you spray carb cleaner or WD40, if you hit the leak, the RPMs wil rise (if it's a big leak) or drop if it's a small leak.

RE: Engine not returning to idle correctly
 

As stated above 90% of slow to drop idle issues areeither air or vacume leak.