BOMBARDIER 1996 Ski-doo MX Z440 Handbook page 114

Section 04
ENGINE PREPARATION
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unburned
mixture burns
spontaneous ly...
These shock waves can sometimes be heard as "pinging." While these shock waves can be
detrimental to the mechanical integrity of the engine, it is the excessive heat that causes most
problems in 2-strokes. The piston may expand excessively causing a seizure or the piston may
melt. The melting will occur at the hottest points, which will be right below the spark plug and
around the edge of the piston —often at a ring locating pin. If allowed to continue, a hole may melt
completely through the top of the piston.
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