Like everyone else, I'm gonna say, don't. If you want to ride a kilt while on something with two wheels, do it on a mountain bike or road bike, but I wouldn't do it on a motorcycle. That said, a UK with the modesty snaps (or, in the case of the survival, the modesty toggles) might work, but I wouldn't try it on a trip where you're exceeding 25 mph.

-J