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Quickv4 12-05-2012 12:21 PM

KZ1100 missfires and dies at idle when warm
I just got a 1982 kz1100a as a project. Got it running. Thoroughly cleaned and set the carbs, made sure the airbox boots seated properly and had no vaccume leaks.

The bike runs good when cold, pulls hard, idles well. However, as it warms up, it will refuse to idle and will hiccup when accelrating hard.
When I pull the plugs from when it stalls at idle, all are black, not wet, but dry black, indicating a rich condition or maybe ignition problems?

Im thinking it may be either the coils or ignition pickups..?

Here is a video from a somewhat cold start to warm up...

Dave in Wi 12-05-2012 05:18 PM

Kind of sounds ignition related to me if it runs worse as it warms up.

Tosh Togo 12-05-2012 06:28 PM


Originally Posted by Dave in Wi (Post 20186045)
Kind of sounds like it's too rich to me if it runs worse as it warms up.

Fixt. :1drink

manxkipper 12-06-2012 03:53 AM

Sounds similar to the issue I had many years ago with my Z1300. One of the ignition pickup coils (it had 3) was faulty and only at idle when hot. I assumed the coil was breaking down with heat. Replaced it with one from a Z1000J. No problem thereafter.

Dave in Wi 12-07-2012 06:21 AM


Originally Posted by Tosh Togo (Post 20186519)
Fixt. :1drink

Entirely possible. What's that old saying, most electrical problems are carb related?

Quickv4 12-07-2012 07:03 AM

If it is fuel related, why are all four plus indicating rich?

When I rebuilt the carbs, I did not replace the orings for the pilot jet plugs. Ive read that these plugs force the piolt jet to siphon fuel through the main jet instead of the float bowl. Maybe they are leaky, and the idle jets are sucking in too much fuel??

anotherguy 12-07-2012 08:33 AM

Do you have access to a four gas analyzer?

channelcat 12-08-2012 09:41 PM

if you did not replace the pilot jet o-rings, you did not rebuild the carbs. basic. thanks for the reminder.

metalmechanic 12-09-2012 08:14 PM

Sounds like Ur condenser or capacitor for your ignition is shot. Easy fix. I could be wrong tho.... :)

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