Honda BIG RED 2009 Owner's Manual page 101

Engine Oil & Filter
6. If required, remove the oil filler cap and add the specified oil into
the filler cap hole, up to the upper level mark on the dipstick. Do not
overfill.
7. Reinstall the oil filler cap, dipstick, rubber dust cover and left seat.
Running the engine with an improper oil level can cause serious engine
damage.
UNDER LEFT SEAT
92 Servicing Your Honda
oil filler cap