Yamaha Raptor YFM350S Ower's Manual page 115

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 surface of the spark plug gas-
ket and its mating surface, and then wipe
off any grime from the spark plug
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)
8-10