If registering in Maine is anything like registering in NH then it's a piece of cake. In NH it's like $75 and all it takes is a bill of sale to get registered. I usually write out my bill of sale in the parking lot before I go in the store (joking of course) and that's that. There are many local stores that sell the registrations. Bait shops, mini marts, hardware stores, whatever. You just have to find one that's open and pop in.
85 Tri-Zinger 60
85 ATC250SX
86 ATC250SX
87 ATC250SX
02 XR650L conversion
84 ATC 480R