Just a heads up on a repair that worked better than I expected.
I've had a lot of trouble starting and some of that was down to a blocked idle jet on my 930 Concentric. The carb had been standing for years and the passage to the idle jet seems to have been solid. A lot of poking and flushing achieved nothing so I drilled the jet out to about .05 mm working from the pilot screw side and this allowed me to clear the blockage.
Then got a 5BA tap and re-tapped the thread in the carb bottom face and fitted a screw in pilot jet (020) from a Mk2.
Started straight way and settled to a steady idle. 5 BA tap was about £5 and the jet the same so its a good result for £10.
