The new Honda Monkey (see also the modern Super Cub) already claims 169 miles per gallon, but that wasn't enough for a team of engineers at Acerbis, who fitted one with a custom-designed 28.5 gallon tank to yield 2,599.7 miles on a single fueling. The run won them a spot in the Guinness Book of World Records.
The AC50 project, which has been in the works for two years, started with meticulous 3D scans of the stock Monkey bike. After endless hours of work, modeling tests and many calculations of tank volumes needed to achieve the world record, the team came up with their first prototype design — a 114-liter (30 gallons) tank.
To test the bike's dynamics with different amounts of fuel in the large tank, the team put the modified Monkey bike through a 1.9 km circuit. After a grueling 304-lap test, Acerbis found they needed to use sponges to combat the sloshing inside the tank at the expense of losing some volume. The final tank weighed 15.2 kg (33.5 lbs) and could hold 108 liters.
If you can't tell what part is the tank in the photo, well, it's all tank.
Here's the route: