August 2023 - NGK fitted in 2017, about 8k since, the last time I would have messed with the carbs would have been after going lead free at that time. Again the front pair (on the right) very slightly weaker but less than before, I'll put half a flat on the front carb this time:

June 2026 - due for replacement by mileage but visibly still perfect. Colours closer now although for some reason No.1 and No.3 seem a little lighter than the others:

October 2026 - A few dozen miles since replacement. Noticeably paler, probably a factor of the replaced air filters! Running particularly well in the cooler weather this autumn but probably could do enriching a tad:

Enriched by half a flat, drove a few miles to get it up to temp (albeit on a cool day) and the lifting pins indicated it was rich. The outer electrodes were a nice mid-brown colour before, just the insulators white, so maybe the mixture had been correct. I did notice on my return home that the idle speed was well down - probably only 500-600 rpm, which is perhaps another indication that the mixture now is not as good as it was before. But I'll do some decent running (when I can given Austen and Boelo ...) then check the plugs again.

October 2026: At least I was going to, but decided to take them out anyway and was shocked to see how dark they were for just half a flat:

Needless to say I put them back by half a flat and will see what that does.

November 2026: A good long run, idle speed back to what it was before 1000-1100rpm, and colour very close to what it was in June on the old plugs: