The standard spark plug is shown in the table. The spark plugs should be replaced in accordance with the Periodic Maintenance Chart.
Spark plug removal should be done only by a competent mechanic following the instructions in the Service Manual.
Spark Plug

A. Plug Gap
Coolant Filling
Evaporative Emission Control System (California
model only)Engine Sprocket Removal
Remove:
Engine Sprocket Cover Bolts [A]
Engine Sprocket Cover [B]
Flatten out the bended washer [A].
Remove the engine sprocket nut [B] and washer.
NOTE
When loosening the engine sprocket nut, hold the rear
brake on.
Raise the rear wheel off the ground with the stand. ...
Nozzle Assy Disassembly
Remove the nozzle assy (see Nozzle Assy Removal).
Pull out the secondary fuel injectors [A] from the delivery
pipe assy [B].
NOTE
Do not damage the insertion portions of the injectors
when they are pulled out from the delivery pipe assy.
NOTICE
Never drop the secondary fuel injecto ...
Air Suction Valve Installation
Install the air suction valve so that opening [A] of the reed
faces downward.
Apply a non-permanent locking agent to the threads of
the air suction valve cover bolts [A], and tighten them.
Torque - Air Suction Valve Cover Bolts: 9.8 N·m (1.0 kgf·m,
87 in·lb)
...