Gardeo GTTAC51T-BS675RT16 Manuel D'utilisation page 100

Spark Plug Service
For good performance, the spark plug must be properly gapped and free of deposits.
Disconnect the spark plug cap and remove any dirt from around the spark plug area.
Remove the spark plug with a spark plug wrench.
Inspect the spark plug. Replace it if the electrodes are worn, or if the insulator is
cracked or chipped.
Measure the spark plug electrode gap with a suitable gauge. The gap should be
0.028 ~ 0.031 in (0.7 ~ 0.8mm). Correct the gap, if
necessary, by carefully bending the side electrode with a
suitable tool.
Install the spark plug carefully, by hand, to avoid
cross-threading.
Install the spark plug cap on the spark plug.
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