APRILIA RS 50 Workshop Manual page 39

Routine maintenance operations
To remove and clean the spark plug:
WARNING
Before carrying out the following operations, let
the engine and the exhaust silencer cool down
until they reach room temperature, in order to
avoid burns.
Remove the spark plug cap (1). Using compressed air,
blow all the dirt away from the base of the spark plug.
Using the special spark plug wrench from the tool kit,
unscrew the spark plug. Make sure that no dirt falls into
the cylinder through the spark plug hole. Inspect the
spark plug, and insure that there are no carbon depos-
its nor corrosion marks on either electrode or the
ceramic nose that surrounds the center electrode.
If necessary, clean the spark plug with a proprietary
spark plug cleaner, and a stainless steel brush. Using
compressed air, carefully blow out the spark plug after
you have cleaned it.
Inspect for cracks on the insulating material, electrode
corrosion or erosion, or deposits that you cannot
remove. If the spark plug shows any of these defects,
it must be replaced.
Check the spark plug gap with a thickness gauge.
The gap must be 0.6 - 0.7 mm (0.024 - 0.028 in); if
necessary adjust it, carefully bending the ground
(outside) electrode.
Make sure the gasket is in good condition. With the
gasket on, screw the spark plug into the head by hand.
Tighten the spark plug with the spark plug wrench,
approximately one-half turn after it first snugly con-
tacts the cylinder head.
CAUTION
If the spark plug is new, it should be screwed in,
unscrewed again, then tightened to the specified
torque.
Spark plug tightening torque:
14.8 Ft-lb (2 kgm) [20 Nm].
CAUTION
The spark plug must be well tightened, otherwise
the engine may overheat and be seriously dam-
aged.
Use the recommended type of spark plug only
(TECHNICAL DATA), in order not to compromise
the life and performance of the engine.
Position the spark plug cap properly, so that it does
not come off due to the vibrations of the engine.
Replace the fuel tank.
SPARK PLUG Standard .............. NGK R BR9ES
Alternative ............ CHAMPION RN1C
2-10
........... NGK R BR8ES
Release 00
1
2001-03
RS 50
0,6 ÷ 0,7 mm
(0.024 ÷ 0.026 in)
ch. 2