1974 Ski-Doo Shop Manual, Page 160Get this manual
SPARK PLUG of the engine, decreasing engin speed du to misfiring, reduced performance, and increased fu el consumptionThis is due to loss of compression Other possible causes are: prolonged idling, running th engine with the chok on, or running on too rich mixture du to faulty carburetor adjustment or incorrect fuel andor fuel mixingThe plug face of fouled spark plug has either dry coating of soot or an oily, glossy coating given by an excess either of oil or of oil with sootSuch coatings form conductive connection between the center electrode and ground
BOSCH SPARK PLUG NUMBERING SYSTEM225 -Indicates particular design detail
T, S",d"d typ,
M: Two cycle engineSemi covered front electrode
Heat range: If we consider 225 rating as normal, pi ug with 175 rating is "hotter" and 240 rating iscolder
- W: indicates 14 mm thread M: indicates 18 mm thread
PLUG FACE