How does the choke work on airhead bings?

[mfp4073]

Owners manual does not address this. I am used to manual chokes as found on classic cars/hot rods. Butterfly that restricts airflow thus making it richer that is adjustable from completely closed to completely open.

I know the bings dont use butterflies, its fuel passengers. Then realized that this may not be an adjustable setup. Are these only 3 positions (off, mid, all on choke) or are they graduatingly adjustable (is that a word)?

Does my question make sense? Not sure i am describing it very well.

[Stagehand]

Its more like an enricher circuit. A separate circuit on the inboard side that essentially dumps lots o fuel past the idle inlet. Pretty sure. I would have to go peruse the Bing manual again to be sure of the particular pathway details, but its basically a fourth fuel metering circuit, used only at startup because it would flood the thing otherwise.

[mfp4073]

Thanks for the reply, I got that much..but guess I didnt describe my question very well.

If off is 1, middle is 2, all on is 3, can i set it at say 2.5 in the controls travel? Or is it only a 3 position setup?

[rufusswan]

Set it where ya want, there may be three holes but there are no notches. Once you've used it a time or two, your bike will tell you what works best for the initial fire. In the cold I crank mine on all the way, warmer whether is about 1/2.

Just remember to turn them off a few blocks down the road, as it is just a starting assist, not a "make a cold engine run better" like on a car.

[Stagehand]

Weell, ok paraphrasing the bing book, the slide type carbs had a plunger assembly that let a predetermined combustible air/fuel ratio to enter the carb throat. THe CV carbs are similar but use a rotary valve instead, and the mix is varied by lever position.

Doesnt specifically say there are three positions, although you can feel detentes.

[mfp4073]

Yeah can feel the detentes. Was not sure if there were passages that it lined up, so if you were not on the detentes it was blocking the flow of fuel to the enricher circuits. Since it does not say anywhere specifically "use settings at detentes" I would guess its trimable (again, is that a word?). BMW is pretty good at not leaving you guessing on stuff.