Ski-Doo FORMULA S 1997, Shop Manual

Page: 188 / 926

Section 05 ELECTRICAL
Sub-Section 03 (IGNITION TIMING)
05-03-5
DUCATI CDI SYSTEM
377, 443 and 503 Engine Types
Proper ignition timing is determined by trigger coil
position.
If for any reason, ignition timing accuracy is sus-
pected, it can be verified as follows.
Verifying Magneto Flywheel Timing
Mark Position
Prior to checking the timing, it may be necessary
to verify the position of the timing mark on the
magneto flywheel, for the following reasons:
1. To detect a missing or broken magneto fly-
wheel Woodruff key which would allow a
change of timing to occur, with eventual break
down of the engine.
2. To correctly locate and mark a timing mark on a
new service magneto flywheel.
3. To verify the correct location of the factory tim-
ing mark.
4. To detect a wrong magneto flywheel.
To verify the position of the timing mark on the
magneto flywheel, proceed as follows:
1. Clean the area around the spark plugs, and re-
move them.
2. Remove the rewind starter from the engine.
3. Install the TDC gauge in the spark plug hole,
(magneto / generator side) and adjust as
follows:
a. Position the magneto flywheel at approxi-
mately TDC.
INSTALLATION OF TDC GAUGE
1. Gauge on MAG side cylinder
2. Adaptor lock nut
b. Assemble the gauge to the adaptor and tight-
en the roller lock nut. Do not tighten the
adaptor lock nut.
c. Screw the adaptor into the spark plug hole
and tighten to prevent movement in the plug
hole.
d. Position the dial face toward the magneto/
generator. Move the gauge down until the
needle just begins to move, then move
down a further 5 or 6 mm (approximately 1/4
in). Tighten adaptor lock nut by hand.
4. Locate the piston TDC position as follows :
a. Slowly rotate the magneto flywheel back and
forth across TDC while observing the needle.
Note that the needle stops moving only as
the piston is changing direction.
b. Rotate the dial face so that “0” is in line with
the needle when it stops moving.
c. Again, slowly rotate the magneto flywheel
back and forth across TDC and adjust the dial
face to “0”, until the needle always stops ex-
actly at “0” before changing direction.
d. “0” now indicates exact TDC.
5. Verify the position of the timing mark on the
magneto flywheel as follows :
A17E0YA
2
1