when you take the slide out of the carb there will be a needle coming out of the bottom of the carb. to adjust the needle clip position you have to take the first separate the spring from the top of the slide, then there sre two very small (very easily stripped) brass screws to be removed then you will be able to slide the needle out, there is a clip on the top of the needle that sits in a groove. to move the clip downwards will richen the fuel and upwards will lean it out.