Hanging Idle

Over the winter I took my carbs apart, and did a pine sol soak. Afterwards, I cleaned out al the passageways with carb cleaner, as per the instructional diagram that floats around here. Put the carbs back on the bike and was having hanging idle issues. Rather that attempting to diagnose the issue, I simply purchased new rubber carb boots. The intake, and exhaust side of the carbs. Of course, to my dismay the hanging idle issue still exists.

When I rev the engine, the idle will hang up, and some times even increase slightly. It takes a while to come down,
I have noticed a few things:
1- I sprayed all around boots, top of carbs, choke plunger listening for a change in idle. Nothing.
2- When the idle is hanging, I can usually lower it with the idle screw.
3- If i blip the throttle, sometimes that will cause the idle to lower back down
4- I have inspected the throttle cable area, and where they attach to the carb. Itdoesnt seem like the cable is getting hung up on anything.
5- My air mixture screws were set at 2 turns out. I have fiddled with them a bit, and found the bike idles best at 1.5 turns out.
6- Bike idled and ran fine last summer.

Any thoughts or help would be greatly appreciated.

Thanks

Was the idle hanging before you cleaned the carbs? You may want to check to ensure your ignition timing advancer is operating smoothly. Ed

Yes, they were working properly before the teardown...... Which has me weary.....
Also, just checked the timing advancer. Working properly.

So i've been doing some reading on the subject.. Came across a thread on another forum that was interesting.

In relation to the thread.. I can start the bike without choke very easily.. Does that mean I have the slides adjusted to be too far open? I bench synched the carbs, but maybe I did'nt have the idle knob twisted in enough... When the bike is warm though, I get it to idle at ~950RPM.... Does this sound normal? Should I need choke to start the bike?

murr50 wrote: Also, just checked the timing advancer. Working properly.

You need to take the whole thing apart, clean and lube everything. Don't ASSUME it's good by looking at it.

ok, the only reason I said that was I twisted the mechnism, and it snapped back with no stickyness. I will take it off and lube though... Any suggestions on a lubricant? Not WD-40 I am assuming...

Hi could also be a loose set screw which the mechanical linkage attaches too. These usually have some locktight to keep them from backing off. It doesn't take much play to get a high or hanging idle. Each carb has one which attaches to the horizontal rod which attaches to the throttle cable. Good luck.

These are all good points. The problem is, with a hanging idle it's not just one thing. So you need to really correct the little things like the advancer 110% to narrow down the issue.

I used Lubriplate on my bike. Any light grease will work fine. Really clean it though. Pull the weights and springs off the pins, lightly sand with fine paper or scotchbrite if needed.

I burnished Molykote G-n paste into the shaft and inner circumference of the ignition cam. That was 6,000 miles ago and so far it's still working great. Ed

hate to revive this old thread, but it seems I may have found the issue.. I lubricated all parts of the timing advancer, still with the same issue. I have been riding the bike regardless... I find that as long as I sit at stop signs with the clutch half let out, and just hold the bike the revs die down... So it seems that under load, the issue goes away... Which obviously points to the timing advance mechanism.. But seeing how it is completely lubed, I am now assuming it is an issue with the springs.

The other day I was fiddling around with the bike outside my house, and when the idle hung up around 4000 RPM, I stuck something against the magnet rotor, to take it out of the advance position, and sure enough, the revs dropped.... Anyhow, this basically confirms the timing advancer as the culprit. Now the issue is traking down some new springs for that thing... Anyone know what type of spring load these require?

Thanks so much for following up on this thread! I'm having the exact issue right now and came across this thread after searching. So many times I read all the way to the end of a thread and find there's no ending! :S

I'm not sure about the springs...I'll let you know if I find anything. I have a feeling my problem might be the same thing.

Just a quick update for future reference. The problem I was having was on my '78 KZ1000A. I had converted the point style ignition to a newer electronic style from a '79-'80 KZ1000. I replaced the point style rotor with the electronic style rotor but still used the original advancer assembly. Now that I look more closely, the springs for the points advancer are much weaker...probably because there is a lighter, round rotor, not a big cam shaped rotor. Anyway, I replaced the point style advance assembly (marked "1003") with the newer style (marked "1009") and no more hanging idle!!

I've searched all over looking for a source to buy new springs and have had no luck yet. They aren't listed in any parts diagrams and I can't find anybody else that has sourced them. I'll update if I get more info......