Honda FourTrax Rancher TRX420FE1 2019 Owner's Manual page 163

NOTICE
An improperly tightened spark plug can damage the engine. If a
plug is too loose, the piston may be damaged. If a plug is too tight,
the threads may be damaged.
10. Connect the spark plug cap. Take care to avoid pinching any
cables or wires.
11. Install the remaining parts in the reverse order of removal.
Spark Plug
Servicing Your Honda 153