My clone refuses to idle properly, I've struggled with it for awhile and can't get it right, I use a .625 crab with 38 main jet and stock idle jet, the way its set is when the adjustment is all the way in then the engine sounds ok, but I've got the rpm too high and is engaging the clutch, also sometimes when it dies it blows black smoke out the carb, checked timing and valves. Runs great any other time just not on idle.