McCulloch B40 P ELITE Operator's Manual page 23

MAINTENANCE
If the machine is low on power, difficult to start or runs
poorly at idle speed: always check the spark plug first
before taking any further action. If the spark plug is dirty,
clean it and check that the electrode gap is 0,9-1,0 mm.
The spark plug should be replaced after about a month in
operation or earlier if necessary.
0,9 - 1,0 mm
CAUTION! Always use the recommended spark plug
type! Use of the wrong spark plug can damage the piston/
cylinder. Check that the spark plug is fitted with a
suppressor.
–
English 23