Where is drain plug on a Yamaha 1981 xt250?

The oil drain plug is at the very bottom of the motor. It's where you'd expect but doesn't look like a normal plug. Look for the round cutout in the skid plate, about 3 inches big. Turning the bolt actually removes a round disc which will then drain all the oil -- and fast! The disk has an O-ring around the lip, and houses a spring and screen which will pop out when the oil is drained. Keep an eye on those parts and how they came out so you can reassemble the same way. Hope this helps! My '80 xt250 just turned 20k miles!