Clean the air filter
What goes in your motorcycle doesn't always come out. And a lot of what goes in passes through your air filter.
That means if your air filter isn't clean, or, in some cases, properly oiled, you could be cutting off airflow to the cylinders and even allowing in foreign abrasives (dirt, dust or worse), where they can grind away at your valves, internal bearings and cylinders.
So do yourself a favor. When it comes to air-filter maintenance, follow the recommended schedule as a minimum. And if you ride in particularly dusty or dirty environments, clean or replace the filter more often. often.