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'83 R100RS Carb Reassembly

Steven Shockley
Active Member Expired Membership

My RS has been setting in the garage for the last year. I could start it but it would immediately stall out. Given the crap gas out there these days I decided to replace the fuel and pull the carbs to clean them up and replace o rings, etc. (Using the gasket/o ring/diaphram kit from EuBMW).

I removed the throttle disc and pulled the throttle shaft to replace the o ring. My throttle disc was marked with "10" on the disc. I carefully wrote down that the "10" goes back in the inside 6 o'clock position. I then come across a very good writeup about rebuilding the carbs and it says the 10 goes in the inside 12 o'clock position.

I then realized that it depends on which way you have the carb oriented, and I did not make note of that when I pulled the throttle disc.

So can anyone tell me which way to orient the carb body and what position the throttle disc goes based on that orientation?


Topic starter Posted : 05/10/2020 11:17
Richard Whatley
Member Moderator

In instances like these, preparation is your friend. Your smart phone camera can easily record hundreds of details before disassembly at zero cost. Next time you'll know.

For the present, I'd sit down down and Google "bing carburetor" then select the "Images" button and scroll through the photos that Google finds for you. Something you can use will pop up.

[color=blue]Don't hide 'em, Ride 'em !!

Posted : 05/10/2020 11:36
Scot Marburger
Member Moderator

If you look closely at the top and bottom edges of the disc, you'll see that they're beveled at an angle. That angle lets the edges of the disc seat in the carb throat, almost completely closing it off. When the disc is installed correctly on the butterfly shaft, the lower edge of the bevel will be oriented so that it faces the body of the carb. Install the disc in the butterfly shaft, put the screws in, but leave them loose. Put the linkage piece on the outside of the carb to lock the butterfly shaft in place. Now slowly rotate the shaft to move the disc into the carb throat. If it's oriented correctly and in the right position, you'll only see the very thinnest of slivers of light if you look through the carb throat with the light behind the carb. You also won't see any of the bevel face, as it will be seated against the carb throat.

Pretty sure that there's an article I wrote on rebuilding the Bings on my R100GS in the Tech Tips section of this web site. It has photos of what I described above. If you can't find it there, look in the R100GS pages at

Good luck, and let us know how you make out.

Posted : 05/10/2020 22:15


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