Husqvarna 122 HD60 Workshop Manual page 41

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.
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.
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.
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