Since I only get 14 mpg, I am nearly ready to build a bike. My only concern is that I am not exactly light. Like 300 lbs not light. As such I am pretty sure a 50 cc motor is not up to the job of carrying me to work at a decent pace. Can anyone point me in the direction of what size /type of engine l might need? The route I use to get to work is mostly level with a few hills in each direction.