Beta RR 4T-250, Workshop Manual

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14
Spark plug
Maintaining the spark plug in good condition makes for reduced
fuel consumption and optimum engine performance. It is prefer-
able to remove the spark plug when the engine is hot (obvious-
ly after switching it off) as the carbon formation and the colour of
the insulator provide important information on carburation, lubri-
cation and the general condition of the engine.
NOTE:
spark plug is black: mixture is “rich”
spark plug is light brown: mixture is correct
spark plug is white: mixture is “lean”
To avoid serious hand burns, wear protective gloves and
perform the operation with great caution.
To perform the check, simply remove the spark plug cap and un-
screw the spark plug using the spanner provided. Carefully
clean the electrodes using a wire brush. Blow the spark plug
with compressed air to prevent any residues from getting into to
engine.
Using a thickness gauge, check that the spark gap is 0.6-0.7
mm. If necessary, correct the distance by bending the earth
electrode.
Also check that the insulator is not cracked and the electrodes
are not corroded. If that is the case, immediately replace the
spark plug.
Perform the check by referring to the indications provided in the
table Maintenance in Chapter 3.
Lubricate the spark plug thread and, when the engine is cold,
screw in the spark plug by hand until it stops and then tighten it
with the spanner.
NOTE: Always use NGK DCPR 8 E spark plugs.
Workshop manual RR 4T - 250 - 400 - 450 - 525