Condenser: Location, Removal And Replacement; Spark Plug: Checking And Re-Setting The Gap - Honda CG125 Service Manual

and battery arrangement connected as shown in the
accompanying diagrams. Should any of these checks not
produce the expected result, the coil should be removed and
taken to a Honda Service Agent or Auto-Electrical specialist for
a more thorough check.
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Condenser: location, removal and replacement

1 A condenser is included in the contact breaker circuitry to
prevent arcing across the contact breaker points as they
separate. The condenser is connected in parallel with the points
and if a fault develops, ignition failure is liable to occur.
2
possible that the condenser is at fault. To check, watch the
points via the rotor apertures when the engine is running. If a
spark occurs across the points and they have a blackened and
burnt appearance, the condenser can be regarded as un-
serviceable.
3 It is not possible to fully check the condenser without the
appropriate equipment. In view of the low cost involved, it is
preferable to fit a new replacement and observe the effect on
engine performance although an approximate test can be
carried out as shown in the accompanying diagram.
4 The condenser is mounted on the ignition coil assembly by
means of a metal clamp. Since this fitting provides the earth
connection of the condenser, it follows that the clip should
make good contact and be tightened fully.
8

Spark plug: checking and re-setting the gap

1 The spark plug specified as original equipment will prove
satisfactory in most operating conditions; alternatives are avail-
able to allow for varying altitudes, climatic conditions and the
use to which the machine is put. It a spark plug is suspected of
being faulty it can be tested only by the substitution of a brand
new (not second-hand) plug of the correct make, type, and heat
range; always carry a spare on the machine.
2 Note that the advice of a competent Honda Service Agent
or similar expert should be sought before the plug heat range is
Fig. 3.3 Ignition timing test using battery and bulb arrangement or multimeter
Chapter 3 Ignition system
altered from standard. The use of too cold, or hard, a grade of
plug will result in fouling and the use of too hot, or soft, a grade
of plug will result in engine damage due to excess heat being
generated. If the correct grade of plug is fitted, however, it will
be possible to use the condition of the spark plug electrodes to
diagnose a fault in the engine or to decide whether the engine
is operating efficiently or not.
3
(indicated by the letter 'R'), where applicable, so that its
resistance value is correct for the ignition system. The same
applies to the suppressor cap; if a cap or plug of the wrong type
is fitted, thus producing a much greater or lesser resistance
value than that for which the ignition system was designed, one
or more components of the system may break down.
4
necessary, alter the gap by bending the outer electrode,
preferably using a proper electrode tool. Never bend the centre
electrode, otherwise the ceramic insulator will crack, and may
cause damage to the engine if particles break away whilst the
engine is running. If the outer electrode is seriously eroded as
shown in the photographs, or if the spark plug is heavily fouled,
it should be renewed. Clean the electrodes using a wire brush
or a sharp-pointed knife, followed by rubbing a strip of fine
emery across the electrodes. If a sand-blaster is used, check
carefully that there are no particles of sand trapped inside the
plug body to fall into the engine at a later date. For this reason
such cleaning methods are no longer recommended; if the plug
is so heavily fouled it should be renewed.
5
the threads sparingly with a graphited grease to aid future
removal. Use the correct sized spanner when tightening the
plug otherwise the spanner may slip and damage the ceramic
insulator. The plug should be tightened sufficiently to seat firmly
on the sealing washer, and no more.
6
stripping the threads from the cylinder head, especially as it is
cast in light alloy. A stripped thread can be repaired without
having to scrap the cylinder head by using a 'Helicoil' thread
insert. This is a low-cost service, operated by a number of
dealers.
A: Connect to earth
B: Connect to moving
contact
Also, always ensure that the plug is of the resistor type
The electrode gap can be assessed using feeler gauges. If
Before replacing a spark plug into the cylinder head coat
Never overtighten a spark plug otherwise there is risk of
C: Battery
D: Bulb
E: Multimeter
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