Ignition Timing - Honda Motorcycle Service Manual

IGNITION SYSTEMS
IGNITION TIMING
Warm up the engine.
For models with multiple cylinders. connect a timing light to
the No. I spark plug wire.
For models with no tachometer, connect an engine tachome-
ter.
NOTE
instructions
and engine tachometer before operating.
Start the engine and check for the following results:
1
-
TIMING LIGHT
Remove the timing hole cap from the engine (refer t o the
Model Specific manual for the location of cap).
.
If the F mark on the rotor is aligned with the index mark on
the case at the correct idling speed, then the timing is
correct.
.
Increase engine speed by rotating the stop screw. on the
INDEX MARK
F
MARK ADVA,NCE MARKS
carbureters.
Check if the
F
mark begins t o move when the engine
speed reaches the advance (or retard) start rpm. (This
inspection cannot be done o n models with a large ignition
~ 6 6
F MARK
IDLE SPEED ADVANCE FULL ADVANCE
(RETARD) (FULL RETARD1
timing variation.)
At full advancehetard rpm, the ignition timing is correct if
I
the index mark is between the t w o advance/retard marks.
I
cannot be checked this way, there are no advance/
retard marks on the rotor for these models. In that case,
check only the F mark position.
Depending on the kind of timing light used when checking the
ignition timing, you could detect abnormal advance timing.
This is because the spark plug wire being measured is not
receiving a negative pulse. (Most timing lights are designed to
receive negative pulses.)
If the spark plug wire being measured is receiving positive
pulses, the input of the timing light will be receiving the
alternated portion o f the weveforrn and the timing light will
flicker.
Reverse the inductive pick-up lead of the timing light, or.
since the polarity o f the waveform has no effect on the spark
plug, connect the ignition primary coil wires t o the opposite
terminals. For double ignition coil types (a single coil firing t w o
spark plugs), connect the timing light to the opposite wire of
the same coil. The correct timing should then be observed.
NEGATIVE
WAVE FORM
the opposite
f
terminals -
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1
f R e c o y 3
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the t m m g Ilghl
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Date of Issue: March, 1995
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HONDA MOTOR CO.,LTD.