Help removing screws from neglected Bing carbs

I needed some parts for my 32mm Bings, so I got a set of rough ones for pretty cheap and need some advice removing the various screws in them such as the butterfly ones. I have one carb setting up with PB blaster and the other in a gallon of parts dip that smells varnishy.


Just seeing if anyone has any advice before I get started. I figure an impact driver would work for most of it, but I'm really after the butterfly shaft and don't think they would fare out too well after being hit with an impact driver.

Unless you feel it is absolutely necessary to remove the butterfly screws, I wouldn't. They have the mfg thread lock on them and if you do remove them. Make sure use thread lock when they are replaced. If they fall out while the engine is running, things get ugly.

Have a look at this website -

http://www.gunsmoke.com/motorcycling/r100gs/carb_rebuild/index.html

About midway through, he goes over the butterfly screws. They are staked in, not thread-locked. If it were me (and I've rebuilt my carbs a couple times) I wouldn't remove the butterfly screws... The idea of re-staking the screws, possibly having one come loose and get in the top end, etc.... it just isn't worth it unless you are positive that one of the seals on the butterfly shaft are bad.

That's just me though.

Too late not to. The dip has killed the shaft oring.
Dremel the threads down to the shaft. Remove.

If you bugger the shaft and screws replacement is abou $10.

Red loctite in upon replacement.

No worries

They may or may not be damaged. If they were mine, I would go ahead an rebuild the carbs and and install them, the butterfly Orings can be installed on a wait and see basis, I have chem dipped a few (Honda) carbs and never had to go back and replace the butterfly orings.

The Bings may be a different story.

Alright thanks for the info! Yea I wasn't going to remove the butterfly shaft but one of the screws was loose and stripped:eek1in the left cylinder carb.
So if I get it out today I can run to the nut and screw place and get replacements.

Looking now like I should of just gotten a new shaft and a set of screws.

+1! The parts are cheap, just do it!

NO!!

these are some of those special screws on your bike that if they come loose you can have some major issues. Don't be cheap and or lazy...Buy the BMW stuff and DO IT RIGHT.

The reason they are stripped is because someone tried to unscrew them without grinding down the peened threads.

Go here: http://www.maxbmwmotorcycles.com/fiche/fiche.aspx


Throttle shaft: $9.83
Screws: 0.67 each

The staking of the screws is no big deal - When I did mine I used a automatic centerpunch to do it...worked a treat

The screws are small and soft

AFAIK it's worthwhile to completely go thru the carbs rather then bandaid

I agree. Removing the Butterflys is not that big as job and getting them back in polace with the screws secures is pretty easy.

To remove the screws strip down the carbs, and mark the butterflies as to top and exterior side. (They're already marked with a dot but I like to have marks that I cant easily ignore.) Next, open the butterflies and using a small flat file, file the shaft until the screws turn out easily.

Once the Butterfly is out, it's easy to remove the shaft and install a new o-ring.

To reassemble, install the shaft, slide the correctly oriented butterfly into place, rotate the shaft so that the butterfly is in closed position and if it is sealed all around with no gaps, check everything three times and then install the clean screws, using a drop of red Locktite.

Don't worry about the screws getting sucked into the engine. If you clean the screws and threads and use red Lockitite, it'll never happen.

just a quick question: i use blue (service removeable) loctite during maintenance or refresh projects on a variety of bikes, never red. i do think i'd use red on maybe clutch nutz or similar but am not sure it's proper on the butterfly screws. the loctite link says red needs to be heated to 500f for diassembly - too hot for these small parts maybe? or maybe not, don't know and thought i'd ask.

In theory yes you need heat...in practice...no a tap bit of heat and a good turn breaks the seal.

I would rather drill out the screw, spend $12 to replace the assembly than have one come loose, end up in the engine, and do god knows what.

When its time to remove the screws again, all you have to do is apply a little heat using a small soldering iron. Those screws only need to come out every 30 years or so!

Feel free to follow some one else's advice but that technique hasn't failed me so far and it's been a while.

I followed Snobums advice and used blue loctite. Is this not good enough? Has anyone had them come out using the blue? Bike assembly is nearly complete and getting the carbs and intake tubes together was a PITA, but I could do it over if I must.

Hey Raven, where did you find the throttle shaft in the schematic? I looked under the R100/7T and couldn't find it.

I tried to drill out the screws in the shaft, but they were pretty stuck.

Also about the floats, I have to run 10% ethanol gas, and hear the alcohol will eat them.

I emailed Bing about the throttle shaft, but they seem pretty high in price compared to Max BMW, think they quoted me at $26 or $29 just for the throttle shaft.

A dremel with an appropiate bit is your best friend on these bikes....I used mine a LOT this winter for a number of things

Look here at this diagram;
http://www.maxbmwmotorcycles.com/fiche/DiagramsMain.aspx?vid=51642&rnd=03252011



Also: Alcohol will not bother your floats...i asked that in my thread.

Yeah, The Bing Agency is an expensive place to buy carb parts. I usually buy my rebuild its from EUBMW. They'll save you a bundle!

Also: Alcohol will eat your floats. They won't die right away but the will deteriorate sooner that if they weren't exposed to that crap.

Bing now sells alcohol proof plastic floats that look like they'll last almost forever. I havent heard any bad reports about em, so next time I need floats, thats what I'm going to buy.

I work on countless bikes that have been running Bing's regular floats in a 10% ethanol mix for decades and they have suffered no issues for it. I have seen no increase in sinking floats whatsoever with using blended fuel with original floats.

I have seen countless problems with Bings first generation "alcohol proof" independent floats just as I have seen tons of problems with the same independent float design in flat slide Mikuni's. What about Bing's very much later new old style float design with new "alcohol proof" floats? They will have to be out for another 20 years before I am going to say they hold up as well as their regular floats. If my original floats that are suppose to melt in alcohol ever actually do melt. I will probably get the regular floats again. They have a known excellent track record.

Thanks for info, I see the shaft on the diagram now. I emailed eubmw to see if they carry a complete rebuild kit. I will stick to the foam floats since it seems that the alcohol wont affect them.

The carbs I have now arent really beat up, but old and the screw heads say they have been apart numerous times or they used bad screw drivers on it. I think I need to do a total rebuild with new every thing, but not sure what actually wears out on these carbs. I have alot of experience with jetski carbs, but they are floatless and needleless

The easiest way to remove those screws is to take a dremel tool to the back side of the screw and remove the peened marks. Do not clean the staining off of the butterflies. You want to use these marks to line them up on the shaft. Install new screws and locktite them as well as peen them over supporting the shaft so you do not bend it. Simple.