I've been over the Alcan eight times - Eastern Wa to Anchorage - but never by motorcycle. Our first trip, up the highway, was the spring I graduated from college - in 1965. It was a true adventure in '65 and fortunately we drove it in a brand new VW Bug. It was a slow, dusty, muddy trip to Anchorage but the little bug made it without a single hitch. My last trip was when we came out in '82, I understand the entire distance is paved now.
I spent my summers working in Alaska, starting in 1960. IMHO only, the spirit that was once Alaska, the days of the Sourdough - they are gone forever and have been replaced with modern technology. Now you can only find what Alaska was once really like by going so very far into the wilderness as to be lost forever.