Throttle shaft

[79914]

hi, I want to replace the throttle shaft o ring but don't want to remove the butterfly is there a way to this? Thanks the carbs are CV Bings regards dave

 

[darryl cainey]

hi, I want to replace the throttle shaft o ring but don't want to remove the butterfly is there a way to this? Thanks the carbs are CV Bings regards dave

In a word No, the small screws have to come out and they are peened over and can't be reused. You have to buy new ones and then peen them over. A job better left to Bing the professionals.

 

[DanHoug]

i didn't find replacing the o-rings was too much trouble... mark the throttle plate with respect to what side is facing out and top/bottom, remove shaft hardware, file off the peened screw threads through the throttle bore, remove plate and slide shaft out. to be obvious, you'll need new screws.

instead of peening the new screws, where you DO risk bending the throttle shaft unless you have really good support on the back side of the shaft (and it doesn't slip), i used red loctite. peening is better but higher risk.

what's nice is that you can take time to really center the throttle plate in the bore as the screws are tightened. maybe a Bing tech would do this well but maybe they are having an off day.

-dan

 

[brook.reams]

The Procedure

hi, I want to replace the throttle shaft o ring but don't want to remove the butterfly is there a way to this? Thanks the carbs are CV Bings regards dave

Hi 79914,

If you want to see what's required and how I do this work, here are the write-ups I posted for a 1973 R75/5 and a 1983 R100RS.

13 BMW R75/5 Rebuild Bing Carburetors & Karcoma Petcocks
13 BMW R100/RS Rebuild Bing Carburetors & Karcoma Petcocks

You didn't say what year/model bike you have, but for the throttle shaft o-ring, it's the same procedure. And, yes, centering and aligning the butterfly plate (which I show) is important to idle performance being equal on both carburetors.

I hope this helps.

Best.
Brook Reams.

 

[lmo1131]

What Brook said.. . .

 

[88bmwjeff]

Brook has a good write up with photos. The one thing that I would add is with regards to aligning the butterfly plate. I start assembly with the throttle shaft, but probably doesn't matter the order. I find it easier to do with the least amount of parts attached. With the butterfly installed and the screws lightly snug, rotate the throttle to the fully close position. While holding the throttle shaft in its closed position, you can adjust the butterfly so there is minimal light protruding around the plate. I usually check the adjustment by holding it up to the sky, but any bright light source would work. When adjusted properly, keep holding the throttle shaft in the closed position and tighten the screws. Once adjusted and both screws are tightened, test the movement again, then remove one screw at a time and apply loctite. If you ask the question, you'll get plenty of responses, but I use blue loctite. I asked around and the greater consensus was that blue was more than sufficient and would not require heat to remove screws in the future. Of course, you could peen the screws again if you prefer. It sounds harder than it actually is. Another trick to help you, it the plate usually has marks on it were the throttle shaft was. Looking at Brook's photo below, you can see the former outline just above the throttle shaft on the left and just below the throttle shaft to the right indicating that the butterfly plate is rotated a few degrees clockwise from its original position. The closer you can get the butterfly plate to its original position, the better, IMO. Brooks, I hope you don't mind me linking a photo to this post. If you do let me know and I will remove the link.

 

[lmo1131]

A couple of other shots. They were online.

You will also want to use a tiny dab of lithium grease in the groove of the shaft. The fit in the bore is fairly tight and when the o-ring is compressed it can put drag on the shaft, preventing it from rotating easily. At least that's what I encountered when I did mine.

 

[79914]

Thanks to all who responded I appreciate your time and expertise regards dave

 

[snowbum1]

The photos of the right way and wrong way of installing the the butterflies were taken from my website,
http://bmwmotorcycletech.info/bingcv.htm

snowbum

 

[PGlaves]

The photos of the right way and wrong way of installing the the butterflies were taken from my website,
http://bmwmotorcycletech.info/bingcv.htm

snowbum

Folks, Just a reminder; when you repost stuff please credit the author. We shouldn't need to remake the wheel but credit where credit is due is important. Please .....

 

[dennisdarrow]

The photos of the right way and wrong way of installing the the butterflies were taken from my website,
http://bmwmotorcycletech.info/bingcv.htm

snowbum

Right on SIR.......... This is why many folks who can, and/or have the knowledge to produce information in a media format do NOT........ Folks have no idea what copyright means and do all that they can to violate it...........THANKS FOR WHAT YOU HAVE PRODUCED for us............. God bless.......Dennis

 

[lmo1131]

Yes, you are correct Paul. My apologies to Mr. Fleischer for this oversight; I'm usually pretty good about it.

 

[brook.reams]

Brook has a good write up with photos. The one thing that I would add is with regards to aligning the butterfly plate. I start assembly with the throttle shaft, but probably doesn't matter the order. I find it easier to do with the least amount of parts attached. With the butterfly installed and the screws lightly snug, rotate the throttle to the fully close position. While holding the throttle shaft in its closed position, you can adjust the butterfly so there is minimal light protruding around the plate. I usually check the adjustment by holding it up to the sky, but any bright light source would work. When adjusted properly, keep holding the throttle shaft in the closed position and tighten the screws. Once adjusted and both screws are tightened, test the movement again, then remove one screw at a time and apply loctite. If you ask the question, you'll get plenty of responses, but I use blue loctite. I asked around and the greater consensus was that blue was more than sufficient and would not require heat to remove screws in the future. Of course, you could peen the screws again if you prefer. It sounds harder than it actually is. Another trick to help you, it the plate usually has marks on it were the throttle shaft was. Looking at Brook's photo below, you can see the former outline just above the throttle shaft on the left and just below the throttle shaft to the right indicating that the butterfly plate is rotated a few degrees clockwise from its original position. The closer you can get the butterfly plate to its original position, the better, IMO. Brooks, I hope you don't mind me linking a photo to this post. If you do let me know and I will remove the link.

Jeff,

Since you attributed the photo to me, it's all good. I believe in the write-up I posted recently on rebuilding the R100RS carburetors, I added some explanation about how I centered the butterfly plate. We both did it pretty much the same way. I just put blue locktite on the threads and then adjust the butterfly as you do and then tighten the screws down. I believe the locktite doesn't setup in the time it takes to do the adjusting, so I had no reason to remove a screw to add locktite after I got the plate aligned.

Best.
Brook Reams.