I can make a few suggestions although reader's discretion is highly advised:
He Can:
1.Install Agha Waqar's water kit (Not recommended).
2.Fit bicycle paddles.
3.Grab the rear end of a tractor trolley or a pick-up for a free boost which in turn will enhance fuel economy.
4.Ask any of our friendly rickshaw driver to put his foot at the rear of his bike. They'll be willing to oblige; trust me! Very helpful people. Alternatively; he can also grab arms of rear motorcycle passengers.
5.Suck (Siphon) petrol from other motorcycles with loose fuel caps. It's illegal, BTW!
6.Make some hydrogen at home like this guy:
Internal Combustion Engines can run on hydrogen with little to no modifications!
7.Take a bus and leave the bike at home.
8.Work from home:
9.Jog to the office. Burn some fat and calories!
10.Ride a bicycle which will save our degrading environment.
11.Strip-off every luxury item form the bike such as mudguards, tappets, seat, headlight, taillight, indicators, battery, wiring etc like this bike:

That ought to enhance the fuel economy by few KM/L. He should also start loosing weight until he begins to look like this guy:
Less weight = Better fuel economy.
Hope it helps!