I toured Alaska on my Triumph Thunderbird 900. I was going to go up to the arctic circle via the dalton and after a conversation with an American biker thought better of it. I scratched the circle itch later in Norway via mo I rama across the high plateue , a better way on a road bike!
Point is that in Alaska the conditions change real quick. I'll give you an example. We were traveling the top of the world highway between chicken and Dawson city on a fine sunny day. The weather changed to rain and the car park type gravel surface turned to wet marbles, going down hill with a bend at the bottom I thought I would have to drop it ! I made it, just. We had buddied up with another biker, an absolute must and having stopped many times for photos only just made the Canadian border which was office hours only.
We were also warned that we would get puntures, we did, one front and one back. It was a whole new ballgame doing that by the side of a dirt road. My bike has tubed tyre you see. Anyhow it was a great trip but my point is , use your head, this is a wild land and Europeans especially find it hard to grasp the dangers. I know this as one of the guys we met in Alaska came home in a coffin. He went under the wheels of a truck after a very long days ride. Do not be fooled by the 24 hour light, be disiplned and get proper rest.
Please do not let this put you off though, its an amazing place.