Yamaha MOTO-4 1987 Owner's Manual page 67

Instead, take the machine to a Yamaha dealer.
You should periodically rernove and inspect
the spark plug becauseheat and deposits will
cause any spark plug to slowly break down
and erode. If electrode erosion becomes ex-
J.
cessive, or if carbon and other deposits are _,,Ci3_
excessive, you should replace the spark plug
with one of the proper type.
Standard spark plug:
. S_)ark
pluggap
CR7HS (NGK)
When installing the plug, always clean the
Before installing any spark plug, measure the gasket seat surface and use a new gasket.
electrode gap with a wire thickness gauge Wipe off any grime from the threads andtor-
and adjust to specifications, que the spark plug properly.
Spark plug gap: Spark plug torque:
0.6 _ 0.7 mm (0.024 - 0.028 in) 12.5 Nm (1.25 m-kg, 9.1 ft.lb)
8-7