My fuel economy is utter butts. What can i do to improve it?

[Ebme Geek]

What do the spark plugs look like, running rich ?
How is your idle, all four chokes closing properly

If motor running smooth and good, plugs nice tan colour, fuel leak ?

I live on an island where the max spead limit is 35 (ya, right  :evil ) and that fuel consumption sounds horrific even to me, something is wrong