1986 Ski-Doo Factory Shop Manual, Page 368Get this manual
Section 04 ELECTRICAL SYSTEM Sub-section 03 (SPARK PLUGS)
EXPLANATION OLD SYSTEM
EXPLANATION NEW SYSTEM
M For Marine Engines, resistant to seawater Electrode with Platinum Tips Silver Center Electrode Wide-Gap Electrodes.060" Wide-Gap Electrodes,044" Wlde-Gap Electrodes.060"
Example:Y
X4 X6Copper core center electrode wide gap .044" (1i mm) wide gap .060" 11.5 mm) special shell or electrode designs
Thread Reach
Thread RaachB
C Thread reach electrode Thread reach tip electrode Thread reach electtode Thread reach Thread reach electrode
Shielded, water-proof; builHn burn-off resistor Plugs for 2-cycle engines Electrodes of precious metals Suppressor resistor, 5000 ohms builtin Silver ground electrode Standard type Semicovered front electrode
-.460" standard .460" extended
314" regular
34"extended tip 3S" regular
Thread reach 31S" extended tip