Honda FourTrax Rancher TRX420FE1 2019 Owner's Manual page 128

Fuel
Fuel Capacity
Fuel tank capacity, including reserve:
3.88 US gal (14.7 ℓ)
Reserve capacity:
1.29 US gal (4.9 ℓ)
When there is only one segment left in the fuel gauge (page 25), fuel
will be low and you should refuel as soon as possible.
Refueling Procedure
Refer to Safety Precautions on page 101.
(1) fuel fill cap
(2) bottom of the filler neck
118 Servicing Your Honda
(1)
(2)