Honda TRX420FPA Owner's Manual page 118

Fuel Capacity
Fuel tank capacity, including reserve:
3.51 US gal (13.3 )
Reserve capacity:
0.69 US gal (2.6 )
The tank should be refilled as soon as possible after switching to reserve,
and the fuel valve should be returned to the ON position after refueling
to avoid running out of fuel with no reserve.
Refueling Procedure
Refer to Saf ety Precautions
(3)
(1) fuel fill cap
(2) breather tube
on page 95 .
(2)
(1)
(3) handlebar cover hole
(4) filler neck
Servicing Your Honda
Fuel
(4)
109