carbs 64/32/203 204

[Happy Eeyore]

I am stumped.  I ordered a carb rebuild kit for 1979 bmw R65 on line.  Everything fit save the slide diaphragms which were too large.  The diaphragms are mounted to the slide with a plastic ring and the slide is pinged to hold the ring in place.  It is not the 4 screw mount.  These carbs are the flat top kind.
Any wisdom or where I might buy the diaphragms which will fit.  I can find no part number of those but clearly there are many and they are different sizes . 

[Barry]

I have the same flat top Bings but I've not yet replaced the diaphragms.  I know that BMW didn't supply the diaphragms as spares, only the the whole slide assembly with the diaphragm fitted.  But they are definitely replaceable because people here and on other forums have done it by warming the plastic ring with hot water to remove and replace it. As far as I know there was no difference in the diaphragm used by flat tops and dome tops with only the 40mm carbs being different. Is it possible they sent you 40mm diaphragms by mistake.

[Happy Eeyore]

Thanks Barry I have ordered another kit for about $11   Bing is too rich for me.  The old diaphragms still look good so back in they went .  Perhaps the next kit will fit and I can put new ones in.  The insides of the carbswere  pretty clean.  Blew out all the holes.  Changed  o rings. Spring missing in idle mix screw so  a trip to the hardware store and it is good to go. New front brake lines next.  So far my walk through the bike has found nothing really amiiss.  Even the steering bearings had good grease. 

[Happy Eeyore]

Carb rebuild kit diaphragms did not fit.  The factory flat top diaphragms are about 78mm in diameter and the 32mm carb rebuild kit from e bay has diaphragms of about 88mm in diameter.  I have contacted Bing but no response yet.  Anyone have a diaphragm source which will fit the flat top Bing 64/32/203 204 or does no one including bing make a diaphragm without the expensive slide attached?  I have found old posts which demonstrate heating the plastic ring and using the old slide  again. Tis a puzzle.

[Barry]

They have sent you the diaphragms for 40mm carbs again.

My flat tops diaphragms are the same size as yours. I can't find specific dimensions for Bing diaphragms but Bings are a sort of copy of Stromberg CV carbs and it's well known that the diaphragms that are used by Stromberg CD150 carbs can be used on 32mm Bings. I found a reference that these Stromberg diaphragms are 78mm dia.   Stromberg CD175 diaphragms fit 40mm Bings and the same source lists these as 88mm dia.

https://classiccarparts.co.nz/stromberg-cd175-carburetor-diaphragm-(sold-as-a-pair)-js499a-seta?search=Stromberg%20CD175%20Carburettor%20Diaphragm

https://classiccarparts.co.nz/stromberg-cd125-cd150-carburettor-diaphragm.-(sold-as-a-pair)-521153-seta

[Bob_Roller]

I've been doing a little searching online the last few days .
The Bing Agency the only official parts source for most of the world .
Located in the midwest US that they recommend replacing the carb top and slide the later style carbs .
Not a great option for you, but it does solve the problem .

[Happy Eeyore]

According to Ted Porter the diaphragms for the 32mm carbs are the same exact size for either the flat top or the dome top.  If he is correct that makes Berry's analysis correct and the ebay guys are sending me diaphragms for 40 mm carbs.  .  In frustration today I placed an order with Euro ME for 32mm diaphragms and I well see if they fit or not.  If not, Ted Porter has the right size for $12.00 each which is a very reasonable amount and he says they just heat the plastic ring on a light bulb and switch out the diaphragms on the flat tops.   I have left an email with Bing and will see what clarifications they may have.  Round and round I go but now I understand a lot more than I did yesterday.  thanks to all. 

[Barry]

I've been doing a little searching online the last few days .
The Bing Agency the only official parts source for most of the world .
Located in the midwest US that they recommend replacing the carb top and slide the later style carbs .
Not a great option for you, but it does solve the problem .

It's the same with most parts suppliers in the UK Bob. They all want to sell you the whole slide/diaphragm assembly at a vast price.  A search on this forum should find members that replaced their own diaphragms by warming the plastic ring. Luck_Lou and Rob Valdez both had flat tops and replaced the diaphragms themselves but neither of them seem to have posted in recent years

[Bob_Roller]

I remember Rob replacing the diaphragm on his carbs years ago and he had difficulty with the plastic retainers . I believe they were brittle and broke. . Don't remember the final outcome for him .
I have not seen diaphragms by themselves, just with the slides as an assembly.
That's why I suggested getting the later parts and not have to deal with this again .