… or what strange causes there are.

I came across another fault today, the cause of which can be found in the manufacture of the Bing's.

I examined carburetors from a 914,
The owner of the plane had been complaining about darker plugs on the right side (1/3) and not particularly nice engine running since the first day.
However, this problem had resolved itself after approx. 800 operating hours.
He had gotten used to it and after all, the engine ran without any other problems.

Now I was amazed when I removed 1/3 of the choke housing from the carburetor.
You can clearly see a milled edge that extends into the area of the rotary choke piston.
During operation, however, the edge was worn away by the rotary piston, so that the choke was tight after the 800 h mentioned.

I suddenly remembered that I had stumbled across a carburetor housing like this before.
I had seen exactly the same picture a few years ago in the course of a complaint.
A milled edge on the carburetor housing reached into the area of the choke plunger where it is supposed to seal. As the rotary piston cannot fully rest and seal here, it is not possible to achieve good engine running with the leaking choke.

Whenever you get Bing's to check, it is advisable to disassemble and check the choke housing.
Make sure that the choke is 100% tight.

Over time, I have gotten into the habit of grinding the sealing surface of the choke on the carburetor housing flat with a diamond tightening stone. This was also urgently needed here.