removing/installing diaphragms?

[AlfromNH]

I bought the carb kit that includes the diaphragms. I read snowbum's article but am still not sure how to get the old diaphragm off the slide, or the new one on. I tried simply pulling it off and only succeeded on tearing the rubber.

What's the trick?  

[Bob_Roller]

I don't have the diaphragms like you have .

But from the post here from members that have, the plastic ring that secures the diaphragm to the slide needs to be heated up to get the diaphragm off .

I'm not real sure, but the plastic rings are difficult to get, the whole assembly, the slide and diaphragm and ring come already put together .

So be gentle in your removal process, or better yet, wait until someone with some experience with this posts about it .

[georgesgiralt]

I bet you've the flat topped carbs.
The diaphragms are said to be non removable and have to be changed with the whole piston which is very expensive. I know some of us had succeeded in removing the plastic band, exchanging the diaphragm and re assembled back the plastic ring without breaking anything. I also know some people whid did destroy the rubber and the plastic band forcing them to spend $$$ at the dealer...
So wait for the expert advice from successful people.... And experience caution and delicacy.

[Luca]

Can't recall how I handled mine, but can you pull those down towards the needle, instead of trying to lift them off the top?

[AlfromNH]

  I'm not feeling real encouraged here. I just looked at the parts fiche- $90 each!  

Help!!

[Luca]

Do you have flat topped carbs?

[AlfromNH]

Flat topped carbs, yeah.

I've done some more reading, and its said to put the whole slide in hot/boiling water and the nylons ring will "slip off".

I tried a heat lamp and the nylon ring loosened up enough to spin freely, but doesn't seem close to coming off. I'll try boiling water sometime in the next couple of days.

[AlfromNH]

Snowbum strongly advises against buying diaphragms directly from Bing. The Bing website has a category for BMW parts... Has anyone tried them?

[Bob_Roller]

Original Bing parts are all I've ever used .

There have been reports from members here, that the aftermarket diaphragms are too thick and inflexible for motorcycle use and cause poor running .

This is one time I strongly disagree with Snowbum's reccomendations .

[AlfromNH]

Thanks Bob. Have you compared prices?

[Kookaburra]

Would advise against using Stromberg replacement diaphrams. They fit and are Ok as an emergency fix but they are thicker and change the way the bike runs.

[Rob Valdez 79 R65]

I always bought my diaphragms from Bing.  I was warned away from the Strombergs by older, more experienced airhead owners.
It was a godsend once Bing started selling the diaphragms and plastic rings separately from the slide.

[steve hawkins]

I have replaced mine on my flat-tops, but I do not recall there being much of a knack.  Or at least I cannot remember that I did anything particularly special....I certainly did not buy the whole unit - So I would not go down that route.

I probably carefully levered them off.  Assuming the old one is definitely toast.

Orientation is critical

Good luck.

Rev Light

[Rob Valdez 79 R65]

Yep - if you are dealing with flat-top carbs, there is the plastic ring to deal with in R/R the diaphragms.
They snap off easily enough (just work a small screwdriver under them), and can be reused as long as they are within tolerance.  (If they don't keep things sealed, they are out of spec...)
With new plastic rings I usually warmed them in boiling water for a few minutes before snapping them in place.

The diaphragms will have two locating tabs.  One on the ID and one on the OD.  They both have slots in the slide/carb body to be matched up.  This ensures that the slide is in the carb correctly.

[AlfromNH]

Thanks guys, seems straightforward enough. I found another thread where the guy used a light to heat the ring, per a Bing tech's suggestion.
http://www.bmwmoa.org/forum/showthread.php?52288-1978-R100-7-Flat-top-Carburetor-Rebuild

Snowbum's site has a ton of great information, but reading it can lead to a lot of over-thinking. For me, at least.