Husqvarna 545RXT AT Workshop Manual page 66

14.5.8 Foreign objects
Everything other than clean air and pure fuel that enters
the inlet port of the engine causes some type of
abnormal wear or damage to the cylinder and piston.
This type of increased wear shows on the inlet side of the
piston, starting at the lower edge of the piston skirt.
The damage is caused by badly filtered air that passes
through the carburettor and into the engine.
Cause:
Faulty air filter. Small dust particles pass through the
filter.
The filter is worn out due to too much cleaning, whereby
small holes have appeared in the material.
Unsuitable filter maintenance, such as wrong method or
wrong cleaning agent. Flock material becomes loose
and holes appear.
Air filter incorrectly fitted.
Air filter damaged or missing.
66 – English
Small score marks and a matt, grey surface on the inlet
side of the piston caused by fine 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 firmly 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.
Action:
Fit a finer grade filter.
Inspect the filter carefully for holes and damage after
cleaning. Replace the filter if necessary.
Clean more carefully and use the right cleaning agent
(such as tepid soapy water).
Change the filter.
Fit the filter correctly.
Fit a new air filter.
Cylinder and piston