APRILIA RX 50 RACING - 2003 Manual page 65

SPARK PLUG MAINTENANCE
(Fig. 67)
From time to time remove the spark plug with the
wrench provided and eliminate the deposits from the
space between the porcelain insulator of the central
electrode and the body of the plug.
Use a feeler gauge to check that the distance be-
tween the electrodes is 0.6 √ 0.7 mm (see figure).
If the distance is incorrect, bend the side electrode
towards the centre one.
Never attempt to bend the centre electrode, to avoid
possible damage to the porcelain insulation.
Use only the correct type of spark plug;
spark plugs with the wrong heat rating
may cause faulty operation.
Recommended spark plug:
NGK BR9 ES.
Fig. 67
65