2003 Ski-Doo ZX Series Factory Shop Manual, Page 256Get this manual
Section 06 ELECTRICAL Subsection 02 (IGNITION TIMING)
6With the TDC gauge indicating specified timing, scribe mark on drive pulley inner half in line with pointer end
Checking Ignition Timing
Use timing light (PN 529 031 900)
A00B4FA
TIMING LIGHT (PN 529 031 900)
A29E0SA
To check the ignition timing, refer to illustration and proceed as follows:
TYPICAL 1TDC gauge indicating specified timing