Chapter 3 Ignition system
61
IGNITION COIL
SPARK PLUG
CONTACT BREAKER
Fig. 3.2 Ignition system: component location
3 Contact breaker: adjustment
1 To gain access to the contact breaker assembly, the left-
hand outer casing should be removed. It is retained by four
screws. The contact breaker is mounted on the stator or back-
plate, and operated by a cam which is fitted to the centre boss
inside the flywheel/rotor. A centrifugally-operated automatic
timing unit (ATU) is fitted to advance the ignition timing as
engine speed increases.
2 Rotate the engine until the contact breaker fibre heel is at
the highest point of the cam and the points are at their widest
opening. Examine the contact faces. If they are dirty, burnt or
pitted, they should be removed for renewal as described in
Section 4 of this Chapter. If the points are in sound condition,
proceed with adjustment as follows:
3 If the gap between the breaker points is not within the per-
missible setting range of 0.3 - 0.4 mm
-
in) when
measured with a feeler gauge, they should be adjusted. Slacken
very slightly the cross point screw which locks the fixed contact
adjustment. It should barely nip the contact support. Using a
screwdriver, open or close the contact, tighten the lockscrew
and check the setting. Repeat until correct.
4 Note: if adjustment has proved necessary, the ignition
timing will have been affected, and this should be checked. It
should be noted that wear in the contact breaker will normally
necessitate its renewal, as no ignition timing adjustment is
provided.
4 Contact breaker: removal and renewal
1 If examination has shown the contact breaker points to be
worn, or if a timing check has shown them to have worn outside
the limits given, it will be necessary to renew the assembly. Do
not attempt to reface the contact breaker points, as this will
make it impossible to obtain the required gap and timing sett-
ings. Use only genuine Honda replacement parts when
obtaining new points.
2 It is necessary to remove the flywheel/rotor from the crank-
shaft in order to gain access to the contact breaker assembly.
This can be expected to be a tight fit on the mainshaft taper,
and although it may be possible to remove it with a con-
ventional legged puller, this course of action must be regarded
as a last resort, and wherever possible, the proper Honda
puller or a cheaper pattern version of it must be used. The
genuine tool is available from Honda agents under part number
- 0010000.
3 Unscrew the centre nut, having locked the crankshaft by
selecting top gear and applying the rear brake, or by applying a
holding tool. Fit the extractor in place, and gradually tighten the
T handle to draw the rotor off. Check the ATU for wear or
damage; if it is stiff in operation it should be dismantled for
cleaning and greasing.
4 Prise off the E clip from the contact breaker pivot post, and
place it in a safe place. Disconnect the leads from the terminal,
and at the same time release the moving contact spring. Note
the order in which the various terminal components are
assembled. Remove the fixed contact securing screw and lift
the fixed contact away.
5 Reassemble the new contact breaker assembly in the
reverse order of that described for dismantling, taking care to
assemble the terminal components in the correct order. Replace
the rotor and tighten the securing nut to a torque setting of 4.0
- 5.0 kgf
(29 - 36
ft). Set the contact breaker gap to
exactly 0.35 mm (0.014 in) as described in Section 3, then
check the ignition timing as described in Section 5.
