What is the life-span of these diaphragms? I just bought a '81 GS850L (65K miles) which needed all 4 diaphragms (BTW, I got an excellent deal on 4 used ones in perfect condition for total from a salvage yard). Some were in worse condition than others. I'm just wondering if it is not recommended to use the gas additive type carb cleaner in carburetors that have these rubber/cloth diaphragms. Thanks for any advice, Mark