If yours is the Dshaped one , then there is a tool , or you can use a jiffy adjuster by using a RED wire crimp butt connector (for joining 2 wires together) , you just heat it and place it on the screw real quick , then let it sit and cool , it will form the D shape and your done , otherwise , it should be a thin , skinny flat screwdriver
The aftermarket screws are much easier to use without loosening and tilting the carb for adjustments , i personally like and use on both my bikes , the Flex Jet , it goes near the outside of the carb by your idle screw , and you can reach down and adjust it while your riding , or you can just get any of the extended screws that have knobs on them
Flex Jet:(i think its the best and easiest to use)
http://www.crfsonly.com/catalog/product ... ts_id/2792
D Tool: (not for adjusting while riding)
http://www.crfsonly.com/catalog/product ... ts_id/3294
T-Handle type fuel screw: (you can reach under the carb to adjust , but is easier to find when off the bike)
http://www.crfsonly.com/catalog/product ... ts_id/1333