Honda FourTrax Rancher TRX420TM1 2020 Owner's Manual page 130

Fuel
Fuel Capacity
Fuel tank capacity, including reserve:
3.88 US gal (14.7 ℓ)
Reserve capacity:
1.29 US gal (4.9 ℓ)
TRX420FM1/FM2:
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.
TRX420TM1:
The tank should be refilled as soon as possible when the fuel
warning indicator comes on.
Refueling Procedure
Refer to Safety Precautions on page 103.
(1) fuel fill cap
(2) bottom of the filler neck
120 Servicing Your Honda
(1)
(2)