1980 KZ750 carb diaphragm streched out/swollen

I had to pull one of my carbs apart today to fix an internal issue but I found the diaphragm is now about a 1/8" too large in diameter to fit together properly. As I try to fit it in position it begins to bunch up and won't all fit in the grove. I could just mash the cover back on but that obviously isn't the proper way to do it. The rubber feels nice and flexible without any defects other than it is just a little streched or swollen. It fit fine a few months ago when I had it apart. Not sure what would have caused it either. Any ideas on how to shrink it back down? I currently have it sitting in the freezer hoping that might help.

Gas makes my large flat bowl O rings swell . Probably the ethanol in the gas is what does it.
Diaphragm in the freezer for 20 minutes would be my only suggestion. Thats what I do with the O rings
Let us know if that worked for you.

Not the freezer, the oven. You need to drive out any hydrocarbons the rubber absorbed. I learned this one time when pulling the fuel pump out of my car. The large sealing O-ring swelled up way too big, but cooking it in the oven at 160F for an hour or so shrunk it back down to normal size.

Did you hit it with carb cleaner? It will ruin rubber parts.
Steve

After 24 hrs in the freezer it was still too large but it was closer. So then I tried the other advice and heated it with my heat gun gently for about 5-10 minutes and that got it close enough to assemble. I never got it really hot, just good and warm. I suspect if I let it sit for a few days or more it would have shrunk back to size. Thanks for the help.