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extremely simple matter, easily carried out even
by the most inexperienced novice if the following
instructions are observed.
The formation of carbon deposit is inevitable
inside the combustion chamber, and at certain
other places, in all internal combustion engines.
because it is either the by-product of the process
of combustion. or a residue from the temperature
effect on the lubricating oil. or both»
If the com»
bustionabie mixture from the carburettor is a. little
on the rich side, di'ze to the use of too large a. jet,
or to unnecessarily long periods of running with
the strangler partly or fully closed, a deposit of
carbon will be formed on the cylinder head and
piston crown. and in the ports, which will be soft
or sooty in texture
If, on the other hand, the
formation of carbon is due to overoiling (La to
running too rich 3 petmil mixture, see page 34).
then the deposit will be much harder and more
difficult to remove.
A study of the carbon deposit will provide a
usefui indication as to its cause, particularly if it
is excessive in quantity.
The main symptoms
indicating an excessive amount of carbon deposit
are an appreciable decline in power, a tendency for
the engine to be rough and overheat. and for it to
run erratically. particularly at low throttle open-
ings.
"Then a stage has been reached at which
these symptoms are evident, decarbonisation is
clearly overdue. and the wise owner of a small
two-stroke Such as the B.S.A. WINGED WHEEL
will find that it pays to work to a. definite schedule
of decarbonisation on a. mileage basis, instead of
waiting for the engine to show signs of distress
before undertaking this work.
For this purpose
Table II. is given as a useful guide.
'14
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