Husqvarna 555FX Workshop Manual page 50

6
Inlet side.
Particles of dust and dirt from carbon-like
deposits on the top of the piston and in the
piston ring groove. The piston ring sits fi rmly
in the groove. Piston material has been worn
away.
The lower part of the piston skirt is thinner
on the inlet side than on the exhaust side.
The piston scored and worn from the piston
ring down on the inlet side.
Extensive damage to the lower part of the
piston's inlet side.
48
Cylinder and piston
Cause:
• Faulty air fi lter. Small dust particles
pass through the fi lter.
• The fi lter is worn out due to too
much cleaning, whereby small holes
have appeared in the material.
• Unsuitable fi lter maintenance, such
as wrong method or wrong cleaning
agent. Flock material becomes loose
and holes appear.
• Air fi lter incorrectly fi tted.
• Air fi lter damaged or missing.
Larger, softer particles that penetrate into the engine cause damage to the piston
skirt under the piston ring as the illustration shows.
Cause:
• Air fi lter incorrectly fi tted.
• Air fi lter damaged or missing.
Larger, harder particles that enter the engine cause serious damage to the underside
of the piston skirt.
Cause:
• Air fi lter damaged or missing.
• Parts from the carburettor or intake
system have come loose and
entered the engine.
Action:
Fit a fi ner grade fi lter.
Check the fi lter carefully for holes and
damage after cleaning. Replace the
fi lter if necessary.
Clean more carefully and use the right
cleaning agent (such as tepid soapy
water).
Change the fi lter.
Fit the fi lter correctly.
Fit a new air fi lter.
Action:
Fit the air fi lter correctly.
Fit a new air fi lter.
Action:
Fit a new air fi lter.
Regular service and inspection.