I am unable to find the default mixture screw setting for this Mikuni BSR33 carb. The screw only unscrews 4 turns and does not unthread out of the carb, (no way to clean it). When I took the carb apart to clean it the screw was set at 1 turn out. I bought this unit when it was only a few months old from a friend so I know it is the original carb. I know most carbs are set at 2.5 turns out, but would like to find out what this specific carb should be set for.