2002 Bombardier Quest 650XT Service Manual, Page 209Get this manual
Section 05 ELECTRICAL Subsection 05 (IGNITION SYSTEM)
SPARK PLUG DISASSEMBLY
Disconnect then remove the ignition coilUnscrew the spark plug one turnClean the spark plug and cylinder head with pressurized airReinstall ignition coil, unscrew spark plug completely then remove it
CAUTION: Severe engine damage might occur or major plastic parts might melt if wrong heat range plug is usedA too "hot" plug will result in overheating preignition, etcA too "cold" plug will result in fouling (shorting the spark plug) or may create carbon build up which can heat up red-hot and cause pre-ignition or detonation