There was discussion at our last NCTR meeting (Northern Colorado Trail Riders) that the rules have changed for registering a dirt bike in Colorado. Seems the Feds have been after all the states to be consistant in their requirements and so everyone has been "encouraged" to follow the Calif example. As I understood the discussion, the new requirements are based on the manufacture date of the bike. Older bikes shouldn't have problems but newer ones will. It has something to do with the wording on the bill of sale/title/MSO. I don't know all the details but if anyone has difficulty plating their dirt bike in Colorado, please post the details so all of us can be aware of the new requirements .