We carry two engine displacements: 48cc and 80cc. Both engines both have a top speed of 25-30 mph when equipped with the standard 44 tooth rear drive sprocket. The 80cc, however, has enough power to accommodate a gear ratio change. The top speed on an 80cc engine when equipped with a 36 tooth rear drive sprocket is 35-40 mph.
Reasons to get a 48cc: some states require registration or licensing for 50cc and larger engines, or you don’t require all that power.
Reasons to get an 80cc: you do a great deal of hill climbing, you need the extra go juice to move your generous bottom, or you just want to go faster.