All around carb tuning on KLX300R
 

It's a 2005 that is stock besides a FMF pipe and it has a weird bog point between idle and 1/4 throttle and it pops. It seems to be running lean. I cleaned the carb really well, all of it and it still does it. I'd like to adjust the pilot screw but I'm not sure how to access it with the plug in the way. How do you get to it?

I also saw that there is an adjuster down by the idle knob but on the opposite side. It looks to be by a vent tube but I'm not sure what it is for.

I guess my question is what type of carb tuning can I do before putting in new jets?

Thanks guys!