1992 Domino/Mira idle problems

Hi All,
I’ve been really enjoying my Little White 92 Domino (L201) for the past year but not long ago, all of a sudden, very rough running, no idle below 2000 rpm. Have done the following:
Took out, cleaned and properly set idle jet adjust (fully seated and two full 360 back) and fast idle on the choke (original setting with yellow paint in place)
Checked all vacuum lines and, as far as I can see or detect, no leaks.
Spray brake cleaner near all potential gaskets and pipes and no difference
Took off, cleaned and factory settings of the carby. All well and clean and no difference
Replaced carby with spare (identical) one and no difference.
Choke checked and set for 23 degrees at appropriate opening angle. All OK
Cleaned and replaced sparks old ones were in good condition and new ones new. Just the recommended ones so no hot or irridium double spark stuff but no difference
Cleaned distributor cap and took off any slight roughness from points and rotor. No cracks and resistance in accordance with original. Cables also OK. Took Distributor off and completely cleaned and checked gaps and seals. All OK.
Exchanged distributor with spare one but no difference
Exchanged coil with spare one but no difference
Checked fuel lines and pump and all OK

The Little Domino always had a rather slow 750 RPM idle and choke was difficult but after carby rebuild last year auto-choke worked well but still slow idle.

Question: What do I miss?? Valves? Idle cut-off (can’t hear or see the latter work…)

Any tips welcome …

PS, the second white Domino (91 model) is making very good progress with a beautifully running engine, new fuel tank and pump, most body repairs done and currently looking for someone able to weld front sub frame.

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Well… After rebuilding the carby, ignition system and flushing everything fuel, losening and temporarily setting the valves for 25 and 35 (they had not been correctly set as there was a huge buildup if carbon over the exhaust valves) I finally found the culprit…

The Idle cut-off solenoid did not open completely… When comparing the two identical solenoids, I found a slight difference in resistance when connecting them to 12V and upon taking both apart, I found that the idle one did not fully open. Took it apart and indeed, it would not fully move and therefor open up. Just enough to make the mixture really, really lean I suppose. A bit of cleaning did the trick… Very easy job as you can just slide out the bronze end and inside you’ll find two sliding pins with a spring. Be very careful not to lose the tiny, tiny spring if you take the solenoid apart!!!

Apart from being a bit tappetty (could not set the valves correctly as did not want to run the engine for long) all is fixed and the little Domino now has a correct idle RPM as well; a problem I had before and could not be adjusted by way of the normal adjustments. Worth properly checking the solenoids if ever experiencing idle problems therefore…

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