hanging idle, no leaks...

Just found in my bike manual database

Full service manual, (German only)

manualedereparatie.info/manuale/Kawasaki...dereparatie.info.zip

www.manualedereparatie.info/manuale/Kawa...dereparatie.info.zip

Michael

Thank you. This is very useful, even if i think I know how to rebuild carb. I did alot of times.
What drives me crazy is the fact my carbs are spotless. Every passage is clean and squirt carb cleaner.
The boots for the zx900a are not the oring tipe. And they are no bolt type.
They are just all rubber. A clamp hold the boots on the head, another clamp hold the carburetor.
They are new.
I tried the mix screw all the way in. Bike obliviously stalls.
Al the way out: smell rich and seem "sleepy" i dont know the right word.
In both situations no change the hanging idle.
I think the carb have something wrong i cant find.
The engine had this issue since i bought the bike :negletted.
I thought a carb rebuild and new boots will cure it, but no glory.

When engine is hot, if i pull the choke half way the rpm go higher. If i pull the choke full the bike stalls.
I adjusted the idle know with engine very hot at 900rpm. Nothing. If i rev it, still hang to 2000 rpm, then slowly drop to idle.
Wtf

Do those carbs have the K-TRIC system? If so, and if it is malfunctioning, it could cause the timing advancer to be unpredictable.

www.kawiforums.com/zzr600-zx-6r-old-scho...ktric-revisited.html

Yes,this sucks but somewhere in your carb system is an air leak.

I have a friend with a Suzuki 800 Intruder with the same problem,i try everything to get
the bike run well at idle,nothing helps. I was totally confused.
At last It turned out that the shaft of the butterfly's ( or Carb body bore ) at this point was totally worn and cause an air leak.
After a we changed the complete carb body with an other used one all got well!
Sync the carbs and choke mechanism on this bike is a real challenge, trust me.

Michael

shamal wrote: ...
Vacuum synch are showing 16cm hg in all 4 carb....

Any unusual differences among the pilot screw settings?

Good Fortune!

Patton wrote:

shamal wrote: ...
Vacuum synch are showing 16cm hg in all 4 carb....

Any unusual differences among the pilot screw settings?

Good Fortune!

no. they are set 2 1/2 turns now but if i try to move the screw the hang idle is still here.
how a electronic ignition can fail and change the timing?
the last thing that remain it's a shaft leak on the carbs, even if i can't find it.
i'm out of ideas.
since the problem become worse when warm i tend to exclude a exhaust leak.
valve clearance it's done.
i have all stock except the mufflers : they are two marving replica of the OEM mufflers.
can be the exhaust too restricted? causing some back pressure? i really don't know.


EDIT
i talked with a eletronic techinician. he say the 34 years old electrolitic condensers inside the CDI box can still work , but he is SURE they are pretty dry and for SURE does not work so well...
in any words: a cdi can keep sparking but maybe some parameters can change.
i think it's time to try another CDI..
and at all the problem was present before the new boots and rebuilded carbs. ..
the bike is showing the same, identical, sympthoms as before.

650ed wrote: If you haven't already done so, try this -

Disconnect the throttle cables at the carbs. The start the bike and give it some revs by manipulating the throttle at the carbs using your hand. If the revs still hang you have ruled out the cables and throttle grip as a possible problem. If the revs still hang you have identified the problem which should be easy to correct by lubing the cables and throttle grip. Ed

This.

I'd disconnect the throttle cable(s) to eliminate the control. If you haven't found the issue yet, you need to narrow down options. You're not adjusting the idle by the cable, right? Is there proper freeplay in the throttle adjustment? Is the end of the grip rubbing on the handlebar? Is the throttle housing clean?

Of course i don not use the cable to adjust the idle. I use the knob
Cable is not the problem, i have no more possibile freeplay but i have at least 2 mm of freeplay. When i shut the gas off the butterflies snap return with the "TACK" sound.
Whats your thoughts about my post above about ignition?

I've seen MANY times people adjusting the idle with the throttle cable.

Since you haven't found anything yet, I would disconnect the throttle cable to be 100% sure it's not the culprit. Has the bike ever run properly before? In my experience, CDI's either work or don't.

Those carbs have diaphragm slides, one could be sticking. Try spraying the slides with WD and see if it still hangs.

Kidkawie wrote: I've seen MANY times people adjusting the idle with the throttle cable.

Since you haven't found anything yet, I would disconnect the throttle cable to be 100% sure it's not the culprit. Has the bike ever run properly before? In my experience, CDI's either work or don't.

Those carbs have diaphragm slides, one could be sticking. Try spraying the slides with WD and see if it still hangs.

slides are not sticky, i have just finished rebuild the carburetors.
i will try disconnect the cable but i think if a cable it's sticky when engine is hot, it should be sticky even when engine is cold.
when cold the rpm drop quick..
in the cARBURETORS all it's moving free. all new lines and oring as i said above . the bike is doing this thing since i bought her. all the new components in the intake system, igniton coils, wires, boots, plug and caps.. etc etc and she is still doing the same identical thing!!!!
CDI can fail too, as i read on the web.
uff

Im going to check again after i triple checked it my cam timing when i changed the cam chain. I tought this low vacuum reading while synching (14cm hg) and the hot engine hang idle can be fault of a tooth of on the cams.
Im pretty sure the cam timing its ok , but i want to check it again.
If the engine is a tooth of on one cam, will be the engine so easy to start , cold or hot? Will be the bike so plenty of power? I really dont know if a single tooth off can make the engine hard to start or something. All i can say is the bike on the road its fast , responsive under load, and can reach 100 mph in a bit...