You want to remove the caps, screws w/o-rings and washers, and clean the passages. Also remove the Pilot Jets and clean them carefully.
Geneally 2.5 turns out is a good starting point, and usually richer that the factory setting (check it before you remove them), which helps with a better idle and smoother throttle transitions off-idle. Idle speed is around 1300 normally. Cold air and gas with ethanol will require a slightly leaner adjustment to be optimum.
Here's more info about the process -
https://faq.ninja250.org/wiki/Intake