The fuel tank looks like the
simplest thing, and it is. The temptation is to use a
regular, rectangular shape can, something from a motorbike
or mower. The important thing is to avoid possible surge
leading no fuel pick-up and the possiblity of stalling. A
long shape like this works really well, and fits anywhere.
Holds about 4 litres.
I drilled out these handy sized bolts
& soldered the pipes in. They are sealed with 'O' rings.
Lug at the top is for the top mounting screw. Mounting point
for the bottom of tank is in the previous photo.