'77 R100S 90K- Noticed fuel? stain at the left carb top and diaphragm interface, removed the diaphragm but found no tears however it was swollen and could not be reinstalled. Picked up a new one from Tony at RePsycle BMW, installed it and noticed it seems to run smoother (imagination?) although I had no complaints before?
Recently pulled 50.9 mpg.
I'm guessing the P/O had new diaphragms installed at the 10K service (about 3K ago) so wondering if swelling is normal due to exposure to crankcase vapors and fuel. My question is; would the swelling alter the vacuum in any way? BTW I plan do to replace right side also.