Fouling plugs at idle....could it be valve seals?

I have a problem with my plugs fouling at idle. Bike is a KZ 1000 LTD, #17.5 pilots, pods and 4in1. Screws are 1 or 1.5 turns out, don't remember right now. After 5 minutes of stop and go plugs are black, although it is still idling well. When I crank it up, I have some misfires for a while, until the plugs "burn" clean. Midrange in WOT is right on, plugs look great.

I tried the original #15 pilots, but the bike idles like crap and still fouls the plugs. Now I read somewhere it could be the valve seals?

Can you "read" from the plug whether it's black because it's running rich or the valve seals are shot?

As always, thanks for any help, this forum is a lifesaver

Sounds like the pilot circuit is too rich. Not sure how you adjust them on VM carbs, but that is where I would concentrate.

That's the obvious thing to look at and I have already done that. I went back to the original pilot jets with the screws 1 turn out and it still runs too rich.

possible bad choke circuit plungers ?.......

any smoke from the exhaust ? if so ,is it blue (oil) or black (fuel)...... :blink:

possibly float level too high

Turboking, how can I tell when the choke circuit plungers are bad? I had the carbs apart, but didn't see anything out of the ordinary.
Bike smokes a bit, but not too bad, I don't think it's blue, looks more black or grey to me.
I have checked float levels with the clear tube method, so should be good.

You have talked about the pilot jets , but you have not mentioned what main jets you are running. Even with a header the later kz 1000 ran a small mainjet. Could be loading up as it is too rich. I believe these where some where around 107.5 stock.

anotherZ wrote: Turboking, how can I tell when the choke circuit plungers are bad? I had the carbs apart, but didn't see anything out of the ordinary.
Bike smokes a bit, but not too bad, I don't think it's blue, looks more black or grey to me.
I have checked float levels with the clear tube method, so should be good.

black smoke means it's fat (rich) :ohmy: ....make sure that your choke lever is working as it should, the screw/spring assy is not loose or moving. :blink: you can push down on the choke plungers to see if it helps...they are probably original ......did you disassemble the choke plungers off the rack and look at them? usually they are rock hard or have cracks and won't seal against the carburetor enrichener seats......they will pull fuel past the plunger at idle, creating a rich condition......just a thought as I have seen that be the problem before :S HTH

after re reading your post :S , + 1 on maybe high float level causing the rich condition.......did it have this problem before you adjusted the float level?

Two things I would mention.....

You would have to look down the intake and exhaust ports to visibly see if there are signs of oil coking on the back side of the valve and valve stem. If they are leaking that badly, then you should see signs of blue smoke coming from the exhaust,

I would say that even with pods and exhaust, you shouldn't have to vary from the stock pilots. If you put the stock pilots back in and it is is acting lean like its popping and surging, then there could be another issue going on such as:

Intake boot leaks
A/F screw leaking air/worn seats
Pilot circuit partially plugged

When you are looking at the plugs, are you looking at the same one, or all of them? Have you adjusted the need position? Did these carbs work for you before and this is a sudden change or is this a new bike to you? Have you been into the carbs deeper than just the jets since you have owned it?

Last think is your charging system and ignition system up to par? If you measure the voltage at the coils during idle, it should be at 13.5vdc or so. If this reading differs from your reading at the battery itself, then you may have a ign. coil connection problem due to resistance. Poor spark energy can lead to fouled plugs and your charging system's performance is worst at idle so any sketchy connections will present themselves there first.

Sincerely do not think it is leaking valve seals.......

Cory

Wow great comments, thanks I try to address them one by one:

Customblue, main jets are 122.5 now. I had 117.5 in there and after 20 miles of (almost) WOT headers were totally blued out and plugs looked very lean. Now with 122.5, they seem spot on at WOT

Turboking, I had disassembled the choke plungers completely and didn't see anything out of the ordinary, however at that time I didn't know about the rich condition, so haven't looked THAT closely. Will definitely do if I take the carbs off next time. I don't think my float level is off. I have used the clear tube method very diligently, so I think I am good.

Cory,
Intake boots are brand new
I don't think the pilot circuit is plugged, had the carbs completely disassembled.
A/F screws, gaskets, seals are all new from the carb rebuild kit
When I look at the plugs I look at least at 2 at a time and always take two different ones, they all look very similar.
Needle is one click richer, mid range is great though, very responsive and correct plug color.
The carbs are off ebay. I bought the bike with 40mm Lectrons and got the current rack of VMs on ebay. The bike has never run better than now, it actually took me a long time to get to where I am, lots of main jet and needle changes.
I had totally disassembled the carbs and went through them.
Someone had told me about the voltage at the coils before, but haven't checked yet.

I think here is what I am going to do in this order:
Measure voltage at coils
Take off carbs, check choke plungers again
Look down intake (and maybe exhaust) ports to check for oil coking
Maybe go back to stock pilots

Thanks again for all that input! And let me know what you think of my approach