I would still check with the police before joyriding around. Yeah, dirtbikes and atv's might be allowed, but if none of those cops ever seen a motorized bike, they may not know if its ok or not. The fact is, dirt bikes and atv's in this instance are off road vehicles that are allowed on road within the reservation. A bicycle is not an off-road vehicle, its an on road vehicle, and adding a motor does not make it a off road vehicle by dmv standards. Now I am sure that even though it is a reservation, some sort of dmv rules still apply. People still have to get car insurance and the only way to do that is to register it. Even dirt bikes and atv's have to be registered to get insurance. So I would find out exactly what they would classify a motorbike as before investing too much in it. Under normal circumstances, I'd say go for it because I myself ride an unregistered bike that would be considered a motorcycle in pa due to its displacement and top speed (98cc, 32 mph, state limits for mopeds are 49cc or less and 25mph, anything over is a motorcycle). But to my understanding, reservations are very tight knit communities, and the police tend to be a little bit more a part of the community than in other places. I could be wrong, but that is my understanding. And one question. Is this reservation big enough to make riding a motorbike enjoyable? I drive the same way back and forth to work every day because I have to, but if every pleasure cruise took me down the same road, it'd get boring real fast. So I'm just curious. And good luck on the reservation. I know some of those communities are very poor. I hope you and your wife make the best of it.