Post a picture of the carb if you can showing the top of the barrel where your throttle attaches to. I checked mine and it is a WYK-61. I may have said WYK-16 in another post so this will correct that. Are you sure there is no needle screw in the top of the barrel? Yours is a 10mm carb and mine is a 9mm. I have another one that is 10 or 10.5mm I intend on trying to see if I can squeeze a bit more power out of it. I do know guys have had issues with tuning with only one needle.