In the nebulous world of legal or allowable where it concerns motorbikes, the concerns of many here seems silly. Where commercial air travel is used, I know for a fact that gas chain saws and other similar things are checked as luggage every day. Gas scooters too. Ever flown Southwest Airlines - watch what comes down their luggage claim belts. Also consider this amazing fact: I and thousands of other have had motorcycles flown with them on the same passenger aircraft. Yeah, you pay a premium but its with you. - Sometimes you even ride to and away from the departing and arriving airport!
Think about the number of times that airlines have ever asked you about your checked luggage. If you are even slightly worried, do curb side check in. Its amazing what a five will do.
Since 9/11, there are many who readily lay down instead just going forward with their plans. If you worry about what the government or other authority says... Maybe you should give up your questionable, nonauthrized or unregulated motorbike as clearly this unacceptable to many in our society or deemed "illegal".
In the world I know and we live, bold thought, initiative and actions reap the most rewards. God help us if we live like sheep and live to serve the shepards.
Be bold and take chances - just like a great morning ride.