Emptied the tank, dismantled the pet-cock and the filter inside the tank. The filter was as I suspected clogged with small flakes of paint. I cleansed it all out with compressed air and put it back in place.
The engine still stutters a little when I try to accelerate from 2,800 rpm but not at higher rpms. I might have to check the carbs, even though they were thoroughly checked 3,000 miles ago.
Apart from that the engine which has done 60,000 miles is running very well, especially after the cleansing of the fuel filter.
Thank you for your inputs
greetings from a warm and semi grey north
Speaking of filters: There must be a four-letter word filter on this forum, English not being my first language I made the mistake of hyphenating the word petcock which immidiately became something I do not know what is: a pet-cock ??
trolle