All sorts of weird stuff can happen in your fuel. I had Hayes neoprene for clunk line, penz air cooled, and my local gas cause a weird silt in my carb screens....two different engines, same exact setup. Changed to tygon and problem is gone. I now also use a Walbro felt clunk and a Dubro final filter right before the carb. My engines have never run better (thanks Jody). I switched to Stihl Ultra 50:1 as well.....Jody again.
