I have an 06 crf50, with a twin air airfilter and modded stock exhaust(no inner baffle and shimmed tip). When first starting it revs really high, I have to turn the idle screw out a lil over 3 turns to get it to idle right, which I know is too way many turns.
With the idle screw like that it still fires up high then when it warms up it slowly idles down. It's also running way too rich.
The first problem with the carb was that the fuel screw was unadjustable(basically flat w/no slot). fixed it with a dremmel, now I can adjust it. Now I see that the main needle only has one slot for the adjuster clip. What is up with this carb?