It is a "cashiyawan" (kaa-she-yaw-won), which is Japanese for "engine sphincter." Don't insert Q-Tips or other objects in it, just a gentle rinse with mild soap will do.I was cleaning it up and I noticed something strange on the bottom of the crankcase. About six inches in front of the gear lever, and a couple inches from the side of the case there is a hole. It just a hole, its smooth, milled, has a lip. Any idea what it is?