Quoted for a second time JohnS.
Here's something I pondered on, we know a Super cub 125 ridden steady can get astronomical MPG, but if it were ridden flat out followed by a 350 Hunter I wonder how much difference there would be? How much easier would the R.E be working?
Looking on Fuelly it looks as though the worst folks with C125's manage is about 120 MPG, the 350 platform Royal Enfields manage about 110 on a good day..... with some posting more.
This depends on how easily a R.E 350 would keep up with an enthusiastic C125... Maybe I'm overlooking the top speed of the C125 & how close to flat-out the R.E would also be...
Maybe sometimes it better not to think...