Poor idling KZ650-D4 after major restoration

All

After some advice as to the suitability of fitting a set of C2 VM24SS carbs onto a KZ650-D4 (SR).

I originally purchased these carbs from a US seller on ebay. They have now been stripped and cleaned and rebuilt. I have kept all the original brass fittings and only replaced the rubber bits. After investigation and lots of useful information on this site, I have identified them as a set that was built for the C2 model. The stamp on the body is 102 2A. They are an airscrew only and have the pilot jet (15), main jet (102.5), jet needle (5DL3-4) and needle jet (0-.
The D4 requirements are the same except for the jet needle (5CN15-4) and needle jet (0-4).

I am running original airbox and 4 into 2 original exhausts. This is a back to factory original restore without wanting to take out a second mortgage...

I now have an idling problem where when cold it idles roughly and until it warms up then won't idle at all.
Looking at the plugs, they are black and sooty which suggests that it is way to rich or an incomplete burn on each firing stroke.

The current state is as follows:-

Valve Clearances
Inlet
1 - 0.14mm
2 - 0.15mm
3 - 0.13mm
4 - 0.13mm
Exhaust
1 - 0.13mm
2 - 0.15mm
3 - 0.15mm
4 - 0.14mm

Battery
New - 12.8V measured.

Fuel
Unleaded 91. Also tried Unleaded 95 but no difference.

Ignition Coils
OEM TEC ZC006-TR12V
The originals were dead and I obtained another used pair with the following resistance measurements:-
Primary windings (spec 1.8 - 2.7 ohms)
1&4 - 2.0 ohms
2&3 - 1.9 ohms
Secondary windings (spec 12K - 18K ohms)
1&4 - 11.1K ohms
2&3 - 10.9K ohms



IC Igniter
As per the service manual, each circuit measures within spec except one.
Black/Yellow & Yellow/Red measure 850 ohms (spec 300 - 700 ohms)

Timing governor
New 21148-1022. Removed the 1016 that had been fitted.
Brand new timing light shows it firing right on the "F" mark for 1&4.
Timing strobes do not flash evenly across all leads. i.e. 4 flashes more evenly than 1, 3 hardly flashes. Very inconsistent.

Pickup Sensors
Brand new.

Carbs - Minuki VM24SS
Ran through the documented procedure for cleaning and checking the pilot, main & choke passages and am now confident that they are each clear. I did have one carb that was blocked at the pilot outlet. I can feel each point is clear when I feed compressed air though them. I have corrected the float height which was way too high and it now sits at 3mm below the main body on each.



I set the airscrews to 1.5 turns out and used the colortune. The engine was warm when I did this. The results were as follows:-
Cyl 1 - No change in color until the the airscrew was all the way in. i.e. color remained yellow.
Cyl 2 - No change in color until the the airscrew was all the way in. i.e. color remained yellow.
Cyl 3 - No change in color until the the airscrew was all the way in. i.e. color remained yellow.
Cyl 4 - Color changed from yellow to blue at 1.25 turns out.

Spark Plugs
Brand new NGK B-7ES. Gap within spec.

Caps & Leads
The original caps were a bit ratty so I obtained a new set. The same problem exists with either set being used. The leads have been replaced with generic new lead.
Originals measured
5.2K ohms
4.8K ohms
4.8K ohms
5.3K ohms
New measured
4.6K ohms
5.4K ohms
5.2K ohms
4.8K ohms

My thoughts are:-

1 - I have a weak spark which does not complete the burn so as time goes by it gets richer within the cylinders so eventually stalls. May be something wrong with the Igniter IC or coils or both.
3 - Should the timing light strobe flash evenly and consistently across all cylinders ? - I would think that they should.
2 - Something is fundamentally wrong with the slide carbs that is not allowing the fuel delivery to be controlled. As stated previously, these carbs are an unknown quantity at this stage. I do have a set of KZ750-E CV carbs but do not want to use them just yet unless I can't fix this issue.

Many thanks and looking forward to hear your thoughts.

Jim

Just tossing an idea here--
The VM29 carbs can be found with different slides, the difference being the size of the cutout at the bottom which can drastically affect idle and low speed operation. One size is specified for Kawasaki engines, the other for Suzuki. I wonder if that is also true of the carbs you have. If so, perhaps you have one that is correct for your application (#4), and three for some other engine?

The plugs should be firing evenly. I'd start there. Buying used coils might be buying someone' else's problems. Igniters can fail in many ways. Might have to go with a Dyna S system being they are still made and parts are easy to get.
JMO
Steve

Does your bike have the factory Kawasaki electronic ignition? I would keep that, it is usually pretty bullet proof.

With the key on what is the voltage you measure at the primary side of the coils? Sometimes the old wiring causes some resistance in this circuit and reduced the power available to the coils.

Sounds like you are way too rich, pilots are correct so the problem could be needles, these are non-adjustable correct?

I would order the correct needles and needle jets for those carbs, and buy mikuni parts whenever possible. However I don't know what the specifics are with the parts you have now, maybe someone more familiar with the different needle profiles can answer.