The word "tune-up" applies mainly to older cars (can still apply to primitive-by-comparison go kart engines) on which you can perform the traditional work associated with the term:
-Spark plug replacement
-Ignition contact point replacement
-Dwell adjustment
-Ignition timing adjustment
-Carburetor idle and mixture adjustment
These are all performance-related. Changing the oil, oil filter and air filter are just regular/routine maintenance. Spark plugs = one down. If it makes you feel like you did a
thorough tune up though, more power to you.