Here is a forum on the Trail 90 and CT110 (105cc I believe on the later), and a thread on top speeds.
http://hondatrailcts.yuku.com/topic/...1#.VLgohjCJOuY
There's a number of these folks getting close to, or a bit over 50 mph.
Mine had a lever to change it internally from street gear to trail gear. It would hit around 30 or so in trail gear as I recall. The older ones had the dual rear sprockets, which were quick change, and a slick setup also.