probst SH-2500-UNI-B Instructions D'emploi page 155

Visually inspect the spark plug. Discard the spark plug if there is
2.
apparent wear, or if the insulator is cracked or chipped. Clean
the spark plug with a wire brush if it is to be reused.
3. Measure the plug gap with a feeler gauge. Correct as necessary
by bending the side electrode.
The gap should be:
0.70 0.80 mm (0.028 0.031 in) −
4. Check that each spark plug washer is in good condition, and
thread the spark plug in by hand to prevent cross-threading.
5. After the spark plug is seated, tighten with a spark plug wrench
to compress the washer.
When installing a new spark plug, tighten 1/2 turn after the spark
plug seats to compress the washer. When reinstalling a used spark
plug, tighten 1/8 1/4 turn after the spark plug seats to compress
the washer.
The spark plug must be securely tightened. An improperly
tightened spark plug can become very hot and may damage the
engine.
−
−
25
0.70 0.80 mm −
(0.028 0.031 in) −