#3 plug is fowling

1980 kz1000 ltd keeps carbon buildup on the #3 PLUG AND BACK FIRERS alot please help me out i just got the bike after 20 years of siting in barn

andysway,

Welcome aboard. Please take some time to use the search function on this website before asking the generous members around here to re-post discussions.

On a bike that has been sitting for so long, likely culprits are a clogged or mis-adjusted carb, a bad plug wire, a bad spark plug or maybe stuck rings.

More information will also be helpful. What color is the fouling? What has been done to the bike so far? Under what conditions does the fouling occur?

Also could be a weak coil.

Check the timing advancer it may be stuck advanced and will make it run terrible at low RPM.

As you sit on the seat, the advancer will be under a CD sized cover on the right end of the crankshaft. It advances/retards the ignition timing by changes in rpm.

To check it, with the engine off, give it a twist,it should return to it's original position, if it is stuck, remove and clean it.

Keep track of how it's installed as it can be installed 180 out. Light oil for a sewing machine or 3-in-one oil works good for this.

Lubricate the spring pivots,weights and other moving parts.

thanks i will give this a try in the morning.my plug is just full of soot after short rideit runs great and idles fine

andysway wrote:

1980 kz1000 ltd keeps carbon buildup on the #3 PLUG AND BACK FIRERS a lot...

andysway wrote:

...plug is just full of soot after short ride it runs great and idles fine.

A possible cause might be too high fuel level in carb #3.
Could check using clear tube test.

Good Fortune!

advanser looked ok to me it went right back but gave it some oil to be sure.i did block off the valve cover air inlets and no more back firing,will try fuel level ad witch way is leaner on the fuel/air skrew in or out

andysway wrote:

advanser looked ok to me it went right back but gave it some oil to be sure.i did block off the valve cover air inlets and no more back firing,will try fuel level ad witch way is leaner on the fuel/air skrew in or out

On side-located pilot air screw, turn out counter-clockwise for leaner, as this adds more air to the pilot circuit.

Here's an example of side-located pilot air screw.

Good Fortune!

Check the gap on ur plugs as well.I think Kaw calls for .032 gap but I have a cylinder that runs a little rich despite carb tweaking so I set that plug at .040.Runs much better.Also u said the bike runs ok when warmed up.How do u start it?Switch on,choke out punch the starter button.Dont touch the throttle.These old bikes flood if u look at them cross-eyed.bj

if the sun is on it i do nothing,morning full choke no gas,i live in floida so it is warm here now.

OK. Its 90 here in Tennessee but I still have to choke mine on first start up.Good luck.bj