I knew the carbs were clean and ready to go. But what was impeding the throttle response? Even the slightest opening of the throttle would stall the motor. So it was time to take the carbs off again. Much easier to get them off than to put them back on.
I emptied each carb bowl and got a decent amount of fuel (in the cap) out of each one. So I know all the bowls were getting serviced with fuel.
I checked that the slides moved freely and they did.
Then I took the bowls off and looked again at the float height. Even thought the tabs are bent quite a way down (or up if they are the right way up!) they are still within spec.
Then I saw the needles just below the end of the main jet.
So I took the slides out and looked at how all that was working.
Was the needle too long?
I took the needles out of the slides. In my previous carb strips I had never taken the needles out before. Mainly because I did not have correct circlip pliers. But when I refurbed these carbs I had taken the needles out. The first needle that I had taken out fell out of the slide and I did not notice how they had been assembled. I have what I call an "insurance" set of carbs. So I took one of those apart and examined how the needles were seated in the slides. And there was my problem:
I had assemble the needles with the spring on top. This was pushing the needle deeper into the emulsion tube and preventing fuel from flowing up it. I can't believe I
originally put all four back together like that having not checked the
workshop manual. I console myself with the idea that they may have been
assembled like that by the previous owner. Is that even possible? Or
was it me? Here's the proof it now works:
