Terrible Gas Mileage (<20 mpg) - Possible Causes?

The needle adjusting system on my BMW is different than what I've seen on other bikes and I think it would be really easy for somebody not familiar with Bings to mess up the needle height. I did just that several years ago and my bike was running perfectly well except that the mileage was terrible, and I only messed up the needle on one carburetor.

That's how my bike was when I first got it. One needle at was at position 2 and the other at position 3. It ran fine but improved by 10mpg when corrected. it prompted me to take some measurements and produce a table for future ref.

I did the same measurements and wrote them down, but I lost the piece of paper.

Thanks for that chart. I’m still waiting for the 32 main jets, which are in the mail. But I know for sure that the needles were in the wrong position on both sides. The O-ring had disintegrated on one side, and the other was in the top position. So that is encouraging, maybe the right position, with everything else back to factory specs will do the job. Will report back.