Husqvarna R135 Workshop Manual page 51

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.
50
Cylinder and piston
Foreign objects
Everything other than clean air and pure fuel that enters the engine's inlet port cau-
ses 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
water).
Change the fi lter.
Fit the fi lter correctly.
Fit a new air fi lter.