Dear, I bought my GS150 almost immediately after your one. Mine has just completed 7500Kilometers. The tuning interval that I have found to be reasonable enough is 2500Km. Meanwhile, after every 1000km, do check the oil level and fill-in if necessary (usually a quarter litre is required at maximum) and check the clutch/brakes adjustment. Rest goes fine till 2500KM at least.
Yeah, these Patakhas also made me curious and I thought this is something wrong with the Piston Rings (God Forbid). But when I told to the Suzuki Mechanic, he smiled and said, "Oh sir ji, ap ka carburetor jaldi khali ho jata hay, fuel knob thori si khol dain.. " then he adjusted it a little, my motorcycle's idle RPM increased from 1500 to 1800, all these Patakh Patakh just vanished. plus, the bike's pick and breath has increased enormously.