I have been searching and reading most, if not all, of the threads on the infamous float bowl orings stretching. I took my carbs off my recently acquired 350F and cleaned 2 on Saturday and 2 yesterday. The bike would start and idle somewhat steadily and run smoothly up to near WOT, but at WOT it would bog down and sputter but closing the throttle it would instantly pick up and run again. With those symptoms I was expecting the mains to be either clogged or loose or the like. Also, #1 carb would leak out of the overflow like a sieve unless the engine was running. So, off they came.
I started with #4 then 3 Saturday night. The mains were a little dirty, but not clogged and all the orings seemed to be ok. I cleaned the air jets and all the passages and all the brass went into the ultrasonic cleaner for about 20 minutes each carb. Reassembly was uneventful and even the float bowl orings went back on perfectly. Last night I pulled #2 then 1 apart and found the mains ok, but the slow/pilot jets completely clogged. The pilot on #1 was so clogged that even after 25 minutes in the ultrasonic cleaner and copious amounts of spray cleaner and air pressure I couldn't get it unblocked. I got my old set of guitar strings out and finally was able to clear the passage. Of note, floats on #3 and 4 were correct, #1 was set too low and #2 was too high. But the bowl orings on these 2 carbs swelled way out of proportion to reuse. As soon as I took the bowls off they started swelling and stretching like one of those old carbon snakes we used to play with on the 4th of July.
Finally, my question. I remember reading on one of the threads I read that one member here soaked his orings in something over night to shrink them back into shape. I'd order a new set but from what I've read here it doesn't appear that there are many, if any, available that don't suffer the same fate. (NOTE: Ethanol free fuel ONLY is used in my vehicles)
