I am currently running a 4 stroke 79 cc motor on an Infinity recumbent bike. It cruises nicely at 33 - 35 mph with a top speed of 40 mph when pedaling furiously! I use it for commuting to work 16 miles 1 way. I got it up and running at the beginning of the year and have put over 2000 miles on it so far. I am getting 100 mpg with this setup. It has a CVT transmission with a whizzer final drive on it. Below is the photo
http://inlinethumb06.webshots.com/42...425x425Q85.jpg