Hello all, I have a os 91 fx with about 3 hours on it. I have had a problem with the low end of this motor from the beginning. Top in runs great and it starts very good but when you set the low end needle it runs rough at idle and even misses. Up about half throttle it has a gurgleing sound. I even had a friend that is pretty good at setting carbs and he couldn't get it set either. Any ideas ?.All help will be greatly appreciated. Keep them flying.