One Sooty Plug

[PAULJAC47]

Hi All any ideas on this one kz900 a4 running fine but 1 cylinder runs rich plug is black and sooty,have checked jets.needle,float height,set with gunson colourtune seems set identical to other three pots in all respects, compression is 150 psi same as rest and carbs balanced only thing i can think of is to swap jets with pot that is running bang on? oh and i have tried running hotter plugs starting to run dry of ideas on this one any sggestions as always gratefully accepted Cheers Pauljac..

[Pigford]

Try swapping #1 lead & cap & plug with #4

[PAULJAC47]

Hi Mark tried that tonight to see if problem swapped pots,after high speed(for me )run about 80 miles still same?? will try swapping jets next though bike is running great?

[scott]

I'd be very interested in this thread, my cyclinder number one does exactly the same.....let us know the result. I was going to lower my slide in the number one carb to see if the colour changed.....tried everything you have tried.....shim clearance is ok, swapped plugs and leads, did a compression test 500 miles ago and that was fine....i'll do another comp test tonight. It does change to the correct colour up at about 80mph though.

[RGH]

I had same problem with my Z1B after buying and rebuilding top end. except No's 3 & 4. tryed every trick under the sun, just about to committ hurycury then got a Zedspert to have a look see. turned out previous owner had swapped No 3 & 4 slide needle jets with Z900A4 needles they are slightly different tapper not visible to the eye was just pumping the juice through and fouling plugs in 3klm just an idea to check you never know Hench

[Rich]

tickover or when travelling?

[PAULJAC47]

Seems to be both?

[Pigford]

You defo got over 12v feed to all ignition stuff

[PAULJAC47]

Yes Mark One of the First things i tried,i have swapped mains jets over from 1 to 4 to the naked eye the one running sooty seemed larger?though both stamped up 115 will give a run tommorow to see if any diff......

[Z.O.A]

I had same problem with my Z1B after buying and rebuilding top end. except No's 3 & 4. tryed every trick under the sun, just about to committ hurycury then got a Zedspert to have a look see. turned out previous owner had swapped No 3 & 4 slide needle jets with Z900A4 needles they are slightly different tapper not visible to the eye was just pumping the juice through and fouling plugs in 3klm just an idea to check you never know Hench

I agree with Hench that this could be your problem, I have just ordered up a keyster kit for my A4 carbs after going through everthing else, upon a full strip I found the previous owner had set the needles to the leanest setting, it was still running rich, took out the needle jets and they were out of round and once the throttle started to open it ran shite.
Hope you get sorted

[paulstrees]

Have you tried changing it with HARRY, SWEEP or SUE

[Rich]

check condition of air jets.

[PAULJAC47]

Air jets look to be in good shape air passages are clear?

[floydsz1]

I have just put a keyster kit in my z1a, It ran ok with the old jets etc, just thought id re-new everything in carbs as the rest off engine is new, it runs very rich now and has slight stutter on pulling away.

[PAULJAC47]

If weather is ok Sunday i am going over to the Griffin in Shustoke will be interesting to see how bike runs.one thing i have noticed is that the main jet that is running rich does not seem to have the Spiders web in it?? i have always wondered what thisi does? anything to do with fuel emulsification? any ideas anyone?