Runaway idle but sooty plugs???!

Hey guys
Just nearing the completion of my 78 z400A resurrection and having carb tuning trouble. I'm running a 2-1 from a single VM32. It started up right away first time but needed throttle to stay alive. plugs were soaked and oily. But once a little warm then the idle would runaway. turning choke back on brought idle under control. Everything I thought I knew said lean and/vacuum leak but plugs remain sooty. And actually they plugs got slightly less sooty when I threw in a smaller pilot jet. So why does choke help the fast idle but plugs are still gassy???
I've never done a carb tune from complete scratch before so maybe I don't know where to start! I did the things I know: adjusted float, set pilot screw at 1.5 turns out...

You have to do a complete carb clean.
Some important inner air or fuel ports can be clogged by a long downtime.
The choke enrich the fuel/air mixture and rises the idle for the startup but the pilot and main jet circuit looks like not be fully okay.
This causes a very fat air to fuel mixture that makes your spark plugs.soaked and oily.

But the Carb is brand new, never used. jets are all brand new. The choke actually keeps the idle down, without it, the idle wants to climb. So I guess I don't understand.

Have you try to adjust the idle screw to lower the idle?
Have you adjust the throttle cable right to get the correct slack.? Otherwise the butterflies stay open and rise the idle.
Please upload a picture of your carburetor

Ok, I've been working on it all day and after a few tests rides this is what is happening: I start it with choke and it revs up very high, so I shut off choke and it immediately wants to die. So from then on I have to keep the throttle twisted in order to keep it running. Again, plugs still sooty afterward. my idle adjuster doesn't seem to have any effect whatsoever, I think because I have to keep the throttle so far open to keep it running it's past where the slide would rest on the throttle adjuster. After it's warmed up flipping the choke on immediately kills it.

It looks like there is an air leak some where.
Are you sure your intake rubber boot and your self made 2 in 1 intake manifold are sealing properly?
Ignition timing and cam timing in spec ?
Valve clearance adjust right?
Normally the engine have to run with the pilot circuit only if all requirements are in spec.

I double checked for vancuum leaks. Even added gasket goop to all the intake mating surfaces. Ive never been able to find the exact valve specs for the kz400A but an old kawi mechanic told me to do .01 on intake and ..05 exhaust. timing is good.
I tried an even smaller pilot jet and still no change. I have to keep the throttle open to keep it alive. sometimes the idle will hang on its own without the throttle but then if I blip the throttle the idle will come down and bike dies. Lots of backfiring through the carb as well when its dying or starting up after dying. Plugs still always sooty. WTF???!?!

harmsworthj wrote: I double checked for vancuum leaks. Even added gasket goop to all the intake mating surfaces. Ive never been able to find the exact valve specs for the kz400A but an old kawi mechanic told me to do .01 on intake and ..05 exhaust. timing is good.

Let's start with this -

FIND A DIFFERENT KAWI MECHANIC!

Your "old kawi mechanic" doesn't know what he's talking about!

The spec for the inlet valve clearance is 0.10 - 0.20 mm (0.004 - 0.0078 inch).
The spec for the exhaust valve clearance is 0.15 - 0.25 mm (0.006 - 0.0098 inch)

See www.manualslib.com/manual/849253/Kawasaki-Kz400.html?page=16

Ed

If the choke slows the motor down, then it's too rich.
If the plugs are sooty, it's too rich.
Both pieces of evidence agree with each other.

Your one VM32 carb for two cylinder system must have a good adjustment of the valve clearance for the optimal air/fuel flow!!!
If one cylinder blown back into the inlet port, (blow back by burned gas) because of leaking by a bad valve adjustment, will effect the other cylinder and air/fuel mixture flow and vice versa.

Please add some pics of your spark plugs

My apologies 650ed that was my bad, I meant the kawi mechanic told me .10 for intake .15 exhaust!! which is what I set them at. Is that excerpt from a Kz400A manual? I couldn't find a 400A (deluxe) valve specs anywhere and all the other submodels were calling for vastly different valve clearances.

One exhaust does seem to puff harder on my had than the other, though both get hot and cylinder compression is even at 150psi each.

I totally have been feeling the rich condition but don't understand how that makes sense with the runaway idle(?) I've dropped to a #20 pilot jet and it's made almost no difference to the #35 I had originally. also screwing the pilot screw in completely or out 3 turns does absolutely nothing to the idle.

The blowback only happens when it chokes out and dies and then when I try to immediately start it. When its running (with throttle held open) it runs great.

i will take photos of plugs

How does choke mean too rich?? Doesn't choke add extra fuel to the mix? So if it was rich already the choke would make it worse not better right? Seems like a lean mix would give me a hanging idle which a choke would help by adding fuel...