1975 BMW R90/6 - Rocinante

I wonder if that carb is just worn out. Back when I actively restored antique motorcycles it was not uncommon.
Well... I had thought of that, I guess it's possible. The thing only has 42k miles though and I know these are known to last a long time. The thing did sit w/ slowly decaying gasoline in the tank and carbs for over 30 years and what I cleaned out can be seen in earlier pix on here. The petcocks were really destroyed so it's possible the inside of this carb is as well, however I did a really thorough go-through on the things the other day and it all looked surprisingly good. I can't tell if the float valve seat is bad, but I did manage to do a good cleanup of it and from what I can see looks ok. I think I've seen replacement seats available but I'm pretty sure that's not something I can do myself, is it????
 
Well... I had thought of that, I guess it's possible. The thing only has 42k miles though and I know these are known to last a long time. The thing did sit w/ slowly decaying gasoline in the tank and carbs for over 30 years and what I cleaned out can be seen in earlier pix on here. The petcocks were really destroyed so it's possible the inside of this carb is as well, however I did a really thorough go-through on the things the other day and it all looked surprisingly good. I can't tell if the float valve seat is bad, but I did manage to do a good cleanup of it and from what I can see looks ok. I think I've seen replacement seats available but I'm pretty sure that's not something I can do myself, is it????
I don't have any experience with the the later Bing carbs. The last one I worked on still had a slide and was on a two smoker. I did a search for Bing carb seat replacement. Seems like one of the common complaints is gas puking out of the overflow. The seat looks cheap enough to try replacement especially when compared to the cost of a replacement carb.
 
I don't have any experience with the the later Bing carbs. The last one I worked on still had a slide and was on a two smoker. I did a search for Bing carb seat replacement. Seems like one of the common complaints is gas puking out of the overflow. The seat looks cheap enough to try replacement especially when compared to the cost of a replacement carb.
I was just doing some research on that and, unfortunately it looks like the later 40mm Bings have a seat that can be changed but there doesn't seem to be one available for the 32mm carbs like mine. I can see why. The seat in the 32mm carb is up at the top of a cylindrical hole in the aluminum carb body and that hole is where the body of the needle goes up and down. On the 40mm carb that cylindrical hole for the needle is actually part of the entire seat which presses into the carb body. Also, as I think about it if there were a problem w/ the seat it would be more likely that I'd have a problem w/ too much fuel rather than not enough.

What I've decided to do is attempt to be as precise as possible and use a caliper to get the height of the tab on the float and test it. Then as necessary measure each succeeding change and test so that each adjustment is absolutely minimal until it's right. There has to be a happy medium in there somewhere. If I had access to a 3D printer I'd attempt to print a transparent float bowl so I can see what's happening in there. EME has a set of two available but I'm not going to spend $99 to get them.
 
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