Hi John and Alsancle,
Thank you both very much for your replies.
Everything is pointing towards some dodgey repairs on the carbs. Would either of you happen to know the correct jet size or spec that these carbs should be for this engine?
What seems strange to me is the bottom half of the carb looks a very different colour to the top. Also the letters don’t quite match, but I can’t find much info on these carbs online.