diaphragms rotating on sliders

[garyS-NJ]

taking my carbs apart to clean the bowls and pilot circuit. I have at least one diaphragm that will rotate on the slider. I read somewhere that a dab of silicone will cure this but just read from a diaphragm seller that super glue should be used. Anyone try something that worked. what glue and where and how?.. BTW, the center plastic screws are tight. I also read somewhere that the diaphragm is anchored to the needle which is keyed to the slider.. but I haven't tried to take the needles out the slider. to secure one of the really freely rotating diaphragms, I held the slider and tapped the center of the slider with a hammer so as to sock the plastic ring up against the diaphragm.. not sure if it held.

[garyS-NJ]

carb 2 diaphragm could be turned but carb 3 diaphragm rotates freely with respect to the slider as well as the inner and outer plastic washers. The center metal sleeve is secure within the plastic slider. from the looks of things, it appears that the original diaphragm assembly has it pinched between the plastic washers which are captured between the slider and the center metal sleeve. The manual shows the slider and diaphragm as an assembly. I'm tempted to clean and dry if and then locate the diaphragm tab with respect to the slider and then put some sort of adhesive between the diaphragm and the slider and metal sleeve and tap the thing back together.. It does appear on this loose one that the metal sleeve is not fully seated in the plastic slider..

[Great White]

Unless the diaphragms are not original, they are "keyed" in the carb housing. Should be a little tab that sits in the recess in the groove.

 

Mine came apart, but I just cleaned the slides and bores with a lint free cloth and then reassembled the slide/sleeve with normal hand pressure.

 

been running fine since and that was (I'm guessing a bit) about a month ago now.

 

Ride it back and forth to work every day (unless it's raining buckets that is).

 

A VERY light buttering of silicone probably wouldn't hurt to snug it up some.

 

Just be sure to not use silicon that has that "vinegar" smell. That type attacks rubber and deteriorates it.

 

Not so sure I would use crazy glue, unless you never intend/need to replace the diaphragms....

[garyS-NJ]

good point on the acid based silicone. I'm thinking a forma gasket silicone. but then tapping that inner sleeve in to grab the diaphragm? My question here seems very generic to almost all old BDS-34's.

 

Yes, I have the tab on the outter edge of the diaphragm that keys to the carb body. but if the slider can rotate with respect to the diaphragm, then it can spin and loose its orientation with the carb body (there's a hole on the bottom of the slider that's supposed to stay there). Also, if it can rotate so freely, then it's unlikely to hold the right vacuum.

[garyS-NJ]

found it here: http://www.venturers.org/Tech_Library/index.php?action=article&cat_id=001010&id=88

[Great White]

good point on the acid based silicone. I'm thinking a forma gasket silicone. but then tapping that inner sleeve in to grab the diaphragm? My question here seems very generic to almost all old BDS-34's.

 

Yes, I have the tab on the outter edge of the diaphragm that keys to the carb body. but if the slider can rotate with respect to the diaphragm, then it can spin and loose its orientation with the carb body (there's a hole on the bottom of the slider that's supposed to stay there). Also, if it can rotate so freely, then it's unlikely to hold the right vacuum.

 

Slider is not supposed to rotate in the diaphragm....

[Great White]

found it here: http://www.venturers.org/Tech_Library/index.php?action=article&cat_id=001010&id=88

 

Not a member there, linky no work. Only goes to the general tech library page...

[garyS-NJ]

I used a spark plug socket to tap the metal sleeve into the sliders which pinches the diaphragm between the plastic washers. This seemed to work but reving the bike I saw one slider stop moving... I pulled that slider and found that it worked itself loose again. So then I pried it apart a little and dabbed contact cement between the metal sleeve and the plastic slider (inside the slider) and then tapped the sleeve into the slider to pinch the diaphragm and let the adhesive set up. The bike still wouldn't rev without popping out the carbs so I suspect the Pressure sensor which is used for the TCI ignition timing... I'll look at the other sliders and also try it with the airbox on but I don't think this is the problem.

[dna9656]

THIS I KNOW: To bond one surface to another in a fuel-rich environment you gotta use a fuel proof adhesive. Super Glue? Is it fuel proof? I donno, I DO know that you can get a THICK ("gap filling") super glue from hobby suppliers. You can get a Super Glue release agent from hobby suppliers too. Imagine being able to get super glue to give it up....

 

My aluminum sleeve that connects to the diaphragm and plastic cylinder... they are (the 2 plastic rings, and cylinder, diaphragm, and aluminum cylinder) no longer ONE assembly.

How do you fix that?

[syscrusher]

I used Super Glue to seal pinholes in the diaphragms and it didn't seem to be deteriorated by the time I finally got around to replacing the diaphragms.