Husqvarna 243RJ Workshop Manual page 48

6
Small score marks and a matt, grey surface
on the piston's inlet side caused by fi ne
dust particles.
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.
46
Cylinder and piston
Foreign objects
Everything other than clean air and pure fuel that enters the engine's inlet port causes
some type of abnormal wear or damage to the cylinder and piston.
This type of increased wear shows on the piston's inlet side starting at the lower edge of
the piston skirt.
The damage is caused by badly fi ltered air that passes through the carburettor and into
the engine.
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.
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 wa-
ter). Change the fi lter.
Fit the fi lter correctly.
Fit a new air fi lter.