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)Liquid Gasket, Non-permanent Locking Agent
For applications that require Liquid Gasket or a
Non-permanent Locking Agent, clean the surfaces so
that no oil residue remains before applying liquid gasket or
non-permanent locking agent. Do not apply them excessively.
Excessive application can clog oil passages and
cause serious damage.
...
Valve Seat Repair
Repair the valve seat with the valve seat cutters [A].
Special Tools - Valve Seat Cutter Holder Bar [B]: 57001
-1128
Valve Seat Cutter Holder, 4.5 [C]: 57001
-1330
[For Exhaust Valve Seat]
Valve Seat Cutter, 45° - 27.5:
57001-1114
Valve Seat Cutter, 32° - 28:
57001-1119
Valve Seat ...
Spring Preload Adjustment
Remove the rear shock absorber from the frame (see
Rear Shock Absorber Removal).
Loosen the locknut and turn out the adjusting nut to free
the spring.
Special Tools - Hook Wrench T=3.2 R37: 57001-1539
Hook Wrench R=35: 57001-1580
To adjust the spring preload, turn in the adjusting n ...