Diaphrams Shrink or Shrunk - too small to go back in Carb now

[Guest]

Hi All,

I've had a couple project GS650s for a couple years. I started a BS32 rebuild a couple years ago and left 3 of the 4 diaphrams out of the carb on my desk. Now, these 3 diaphrams have shrunk to the point where I can get them to sit in the groove well enough to get the top of the carb on. I've read that these rubber component dry out and can shrink. There doesn't seem to be a consensus as to what the best chemical is to rejuvenate the elasticity of the rubber so I thought I should ask you good people at GS resources what products you recommend.

So far:
MG Chemical - Rubber Renue http://www.amazon.com/MG-Chemicals-R.../dp/B008O9X3KS
Brake Fluid - DOT 4 was the only specific type mentioned (in a youtube video)
Wash in a Washing Machine or Dishwasher with phospor soap
Silcone Spray of some variety

I thought I'd try soaking in gasoline first as it's essentially mix of a bunch of organic solvents and obviously the rubber is usually exposed to in the carb.

[Steve]

Actually, the diaphragm is only exposed to filtered air, but good luck with your project.

.

[huntb]

I have three for sale. PM me if interested

[tweebs]

Actually, the diaphragm is only exposed to filtered air, but good luck with your project.

.

Ummm... Good point. I would have thought there would be some gasoline vapours making it past the slides but they fit pretty tight.

[tweebs]

Update: I ended up soaking the three carb diaphrams with slides in DOT 4 break fluid for 24 hours. The break fluid did turn from clear to dark brown. It did rexpand the rubber, perhaps a bit too much but they aren't the same original shape. They are now a bit deformed. I've put them back in the carbs and although everything was sealed they don't slide smoothly when the slides return back down. There is a point where they pop/drop as they are coming back down. The rubber is a little deformed. Hopefully leaving them in the carbs will allow the rubber to work itself out.

I'd recommend trying washing the diaphram in hot water to strech them before trying other chemicals.

[JTGS850GL]

I have some new diaphragms as well if you need them.

[tweebs]

Thanks JTGS. After installing them and letting them sit in the carbs for a day they seem to be sliding better. I've installed them on the bike and started tuning, so far so good. Now I just need a big box fan. That air cooled engine heats up quick and those exhaust gases really make me dizzy.