I have not done much with the JDL's (loads with 2f basically same carb), I recently had a JDL running OK with a temporary fuel tank (just running not riding), I quickly cleaned out the tank but I don't think good enough, fresh fuel in and it went down the road about 1 mile absolutely fine. Stopped it and took a picture, it didn't want to restart, it did go but by the time I got back the 1 mile it was down on power! if you take the jet out it looks blocked blow through it and it clears, next time you take it out blocked again. I have had this on the 2f's until you can get the jet properly cleaned out you get all sorts of starting / running / cutting out issues. Hope that helps and do want to get on to mine again to see if I can resolve the problem.