Yamaha KODIAK 400 Owner's Manual page 140

Instead, take the ATV to a Yamaha dealer.
You should periodically remove and inspect
the spark plug because heat and deposits will
cause the spark plug to slowly break down
and erode. If electrode erosion becomes ex-
cessive, or if carbon and other deposits are
excessive, you should replace the spark plug
with the specified plug.
Specified spark plug:
DR8EA (NGK)
Installation
1. Measure the electrode gap with a wire
thickness gauge and, if necessary, adjust
the gap to specification.
Spark plug gap:
0.6–0.7 mm (0.024–0.028 in)
a. Spark plug gap
2. Clean the gasket surface. Wipe off any
grime from the threads.
3. Install the spark plug and tighten it to the
specified torque.
Tightening torque:
Spark plug:
17.5 Nm (1.75 m·kgf, 12.5 ft·lbf)
8-30