Honda FourTrax Rancher TRX420TM1 2020 Owner's Manual page 177

Rear Brake Lever Freeplay
LEFT HANDLEBAR
9/16 – 13/16 in
(15 – 20 mm)
(1) rear brake lever/parking brake lever
Inspection
Measure the distance the rear brake lever/parking brake lever (1)
moves before the brake starts to take hold. Freeplay (measurement
at the tip of the end of the brake lever) should be:
9/16 – 13/16 in (15 – 20 mm)
If necessary, adjust to the specified range.
(1)
Servicing Your Honda
Brakes
167