Honda Motorcycle Service Manual page 390

IGNITION SYSTEMS
The output from the ignition pulse generator is converted into
basic waves A and B
Basic wave A is unaffected by engine speed and remains
constant.
Basic wave B changes its gradient as the engine speed in-
creases as shown in the graph at right.
The ignition timing determination circuit sends current to the
gate of the SCR when a negative voltage pulse from the
ignition pulse generator is input to the determination circuit,
or when wave A becomes greater than wave %The current t o
the gate of the SCR turns it o n and ignites the spark.
Since wave A remains constant and wave B changes its
waveform as the engine rotation increases, wave B becomes
smaller than wave A. As the engine speed increases, the tim-
ing at which wave A becomes greater than wave €3 advances.
When the engine speed increases above N4, ignition timing no
longer advances because basic wave A is not inclined.
At N1, wave B is larger than wave A and so ignition timing is
determined by the negative voltage pulse from the ignition
pulse generator.
PULSE GENERATOR OUTPUT
. )
A
c,
-)
WAVE
FORM A
4+
WAVE FOw
4
>NITION TIMIN(
IETERMINATIOfi
:IRCUIT OUTPUi
4
&
: R GATE INPUT
iNlTlON TIMING
RANKSHAFT
NGLE
d
- -
Date of Issue: March, 1995
0
HONDA MOTOR CO..LTD.