Had a recent experience with the engine missing at part throttle, still business as usual at WOT. Suspected idle jets and had some assurances from others on the board that was likely the case. Weber 40IDA3C, 40 IDA 3-C etc... not sure if the layout is the same on 46's. Anywho...
Very basic procedure but if you haven't done any carb fiddling then it can be a bit daunting with the dated materials on the web for determining exactly where to find the idle jets on the carb body. Lots of brass screws on the outside to choose from and the widely distributed diagrams on the web are primarily from the other side of the carb body. Hopefully this saves someone some time/head scratching and deep reading.
Plan about 30mins for the job, including re-hydration pauses.
Tools for the job:
Pop the lid:
These are the idle jet holders, circled in red. I recommend to clear them one at a time for the sake of organization.
I found a chunk of fuel line rubber (I believe) lodged in the opening on cyl #1.
Here's the idle jet complete with the older:
Pulls apart with bare hands:
Gently clear the blockage by the means you choose. I used a safety pin as I had it on hand to poke only the rubber before clearing with carb clean and compressed air. Take care not to damage any of the metal.
If you have gum/varnish or other deposits then now might be the time to soak the jet with carb cleaner. Clear through:
When reinstalling, I used a very light coating of oil on the o-rings and took care not to over-tighten. These are only gently snug, not "guten tighten". As the age of my rubber fuel lines is unknown, I'll plan on replacing these in the next week and adding fuel filters closer to the carbs perhaps. Paul/1QuickS mentioned enhancing the sealing of the air filters around the edges - I'll likely pursue that as well.