Its pretty easy.
Search in manual/internet what are the ideal rpms of this engine.
Go to workshop who has RPM gun/meter and ask him to set the required RPMs.
Once set you don’t need to change it.
After a cold start, for 2~4 minutes it runs on high RPMs (Auto-Chowk). After that it automatically will stable to desired RPMs as you fixed.
Do it and enjoy the ride.