1999-2000 Bombardier Traxter ATV Factory Service Manual, Page 129Get this manual
Section 05 ELECTRICAL Subsection 05 (IGNITION SYSTEM)
SPARK PLUG DISASSEMBLY
First unscrew the spark plug one turnClean the spark plug and cylinder head with pressurized air then completely unscrewA 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
HEAT RANGE
The proper heat range of the spark plugs is determined by the spark plugs ability to dissipate the heat generated by combustionThe longer the heat path between the electrode tip to the plug shell, the hotter the spark plug operating temperature will be and inversely, the shorter the heat path, the colder the operating temperature will beA "cold" type plug has relatively short insulator nose and transfers heat very rapidly into the cylinder headSuch plug is used in heavy duty or continuous high speed operation to avoid overheatingThe "hot" type plug has longer insulator nose and transfers heat more slowly away from its firing endIt runs hotter and burns off combustion deposits which might tend to foul the plug during prolonged idle or low speed operation