IAME X30 125cc RL - TaG, Assembly Instructions & User Manual

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- 28 - MAN-043E ENG
3.11 SPARK PLUG AND THERMAL DEGREE
The engine is supplied with a standard NGK BR10EG spark plug, which represents a
good compromise between the needs of a good running-in and the racing needs in
normal conditions.
Use of different spark plugs is possible and, as a general information, we are
attaching a correspondence list among spark plugs of other brands, based on thermal
degree which represents the capacity of the spark plug to dissipate the internal heat.
The colour of the various parts of the spark plug more exposed to the combustion
flames gives a good indication on the adequacy of the thermal degree and on the
carburetion. It is necessary though to understand which of the two parameters has to
be changed and only the experience tells how to identify the most proper thermal
degree of a spark plug as lean or rich mixtures can generate the same final look which
can also be achieved with a hot or cold spark plug.
See table:
An excessive warm spark plug shows the symptoms,
listed aside.
WARNING:
Always use a warmer than standard spark plug with
cold or rainy climate.

Extremely clear colour, porous look and
calcification of the electrodes and of the internal
insulation.

Irregularities in the ignition, preignition and
detonation with tendency to perforate the top of the
piston.

Note: some of these symptoms can be achieved
with lean mixtures.
A correct thermal degree shows:

Colour of the insulator end from yellow grey to
dark brown for mixtures respectively lean or rich.
An excessively cold spark plug shows the symptoms,
listed aside.
WARNING:
Always use a colder than standard spark plug with
hot climates.

Insulator end and electrodes covered with black
shady soot.

Ignition difficulties

Note: a wet or oily electrode could also mean an
excessively rich mixture.
COMPARISON TABLE BASED ON
THE THERMAL DEGREE
HOT
BOSCH NGK CHAMPION
WO8CS BR9EG N54R
WO7CS BR10EG N52R
WO6CS BR11EG
COLD